Civil Aviation (Communication Systems) THE CIVIL AVIATION ACT (CAP. 80) PART I PRELIMINARY PROVISIONS PART II GENERAL REQUIREMENTS

Size: px
Start display at page:

Download "Civil Aviation (Communication Systems) THE CIVIL AVIATION ACT (CAP. 80) PART I PRELIMINARY PROVISIONS PART II GENERAL REQUIREMENTS"

Transcription

1 GOVERNMENT NOTICE NO. 75 published on 24/02/2017 THE CIVIL AVIATION ACT (CAP. 80) THE CIVIL AVIATION (COMMUNICATION SYSTEMS) REGULATIONS, Citation 2. Interpretations 3. Application PART I PRELIMINARY PROVISIONS PART II GENERAL REQUIREMENTS 4. Requirements for Communication, Navigation and Surveillance Facilities 5. Certification of Air Navigation Service Provider 6. Approval Requirement 7. Inspections and Audits 8. Sitting and Installation 9. Commissioning Requirement 10. Availability and reliability 11. Test Equipment 12. Record Keeping 13. Documentation. 14. Periodic Inspection and Testing 15. Flight Inspection 16. Operation and Maintenance Plan 17. Training requirements for communication, Navigation and Surveillance Personnel communication, Navigation and Surveillance personnel requirements 18. Proficiency certification program 19. Installation, operation and maintenance of Communication, Navigation and Surveillance Systems. 1

2 PART III AERONAUTICAL TELECOMMUNICATION NETWORK 20. Support of Aeronautical Telecommunication Network Application 21. Requirements for implementation of Aeronautical Telecommunication Network 22. Aeronautical Telecommunication Network Applications Requirements 23. Air-ground applications 24. Ground-Ground Applications PART IV ATN COMMUNICATION SERVICE REQUIREMENTS 25. Aeronautical Telecommunication Network or Internet Protocol Suite upper layer communications service 26. Aeronautical Telecommunication Network or Open System Interconnection upper layer communications service 27. Aeronautical Telecommunication Network or Internet Protocol Suite communications service 28. Aeronautical Telecommunication Network or Open System Interconnection communications service 29. Aeronautical Telecommunication Network Naming And Addressing Requirements 30. ATN security requirements 31. Aeronautical Mobile-Satellite (Route) Service 32. RF Characteristics 33. Priority and pre-emptive access 34. Signal acquisition and tracking PART V PERFORMANCE REQUIREMENTS 35. Designated Operational Coverage 36. Failure notification 37. AES requirements 38. Packet data service performance 39. Delay Parameters 40. Integrity 41. Voice service performance 42. Call Processing Delay 43. Voice Quality 2

3 44. Voice Capacity 45. Security 46. System Interfaces 47. Packet data service interfaces PART VI SECONDARY SURVEILLANCE RADAR MODE S AIR- GROUND DATA LINK 48. Air Ground Data Link Communication PART VII VHF AIR-GROUND DIGITAL LINK (VDL) 49. Radio channels and functional channels 50. System Capabilities 51. Air-ground VHF digital link communications system characteristics 52. System characteristics of the ground and aircraft installations for VHF Air-Ground Digital Link 53. Physical Layer Protocols and services 54. Link Layer Protocols and services 55. Subnetwork Layer Protocols and services 56. The VDL Mobile Sub Network Dependent Convergence Function 57. VDL Mode 3 Sub Network Dependent Convergence Function(SNDCF). 58. Voice Unit for Mode 3 Services 59. Voice Unit for Mode 3 speech encoding, parameters and procedures. 60. VDL Mode 4 radio channels 61. VDL Mode 4 System capabilities 62. Coordination of channel utilization PARTVIII AFTN NETWORK 63. Technical provisions relating to teletypewriter apparatus and circuits used in the Aeronautical Fixed Telecommunication Network 64. Terminal Equipment associated with Aeronautical Radio Teletypewriter channels operating in the band 2.5 to 30 MHz 65. Characteristics of Interregional AFS circuits. 3

4 66. Technical provisions relating to international ground-ground data interchange at medium and higher signalling rates. 67. Aircraft Addressing System PART IX Point-To-Multipoint Communications 68. Service via satellite for the dissemination of Aeronautical Information 69. Service via satellite for the dissemination of WAFS products. PART X HF Data Link System 70. System architecture 71. Aircraft and Ground Station Subsystems 72. Operational coverage 73. Requirements for carriage of HFDL equipment 74. Ground station networking 75. Ground station synchronization 76. Quality of service 77. HF Data Link Protocol 78. Ground Management Subsystem PART XI UNIVERSAL ACCESS TRANSCEIVER (UAT) 79. UAT system characteristics of aircraft and ground stations 80. Mandatory carriage requirements PART XII AERONAUTICAL MOBILE SERVICE 81. Air-Ground VHF Communication System characteristics 82. Single Side Band (SSB) HF Communication System characteristics 83. SELCAL System PART XIII AERONAUTICAL SPEECH CIRCUITS 4

5 84. Technical provisions relating to International Aeronautical speech circuit switching and signalling for ground-ground applications PART XIV EMERGENCY LOCATOR TRANSMITTER FOR SEARCH AND RESCUE 85. Operating frequencies 86. Emergency Locator transmitters Register 87. Specification for the MHz component of Emergency Locator Transmitter 88. Specification for the 406 MHz component of Emergency Locator Transmitter. 89. Transmitter identification coding PART XV EXEMPTION 90. Requirements for application for exemption. 91. Requirements for application for exemption. 92. Evaluation of the request PART XVI GENERAL PROVISIONS 93. Drug and alcohol testing and reporting 94. Change of name 95. Change of address 96. Replacement of documents 97. Use and retention of documents and records 98. Reports of violation 99. Failure to comply with direction 100. Aeronautical fees 101. Contravention of Regulations 102. Offences and Penalties 103. Appeal PART XVII OFFENCES AND PENALTIES 5

6 SCHEDULES THE CIVIL AVIATION ACT (CAP. 80) REGULATIONS (Made under section 4) THE CIVIL AVIATION (COMMUNICATION SYSTEMS) REGULATIONS, 2017 PART I PRELIMINARY PROVISIONS Title These Regulations may be cited as the Civil Aviation (Communication Systems) Regulations, Interpre-tation In these Regulations unless the context requires otherwise - Aeronautical administrative communications (AAC) means Communications necessary for the exchange of aeronautical administrative messages; Aeronautical operational control (AOC) means Communication required for the exercise of authority over the initiation, continuation, diversion or termination of flight for safety, regularity and efficiency reasons; Aeronautical telecommunication network (ATN) means a global internetwork architecture that allows ground, airground and avionic data sub-networks to exchange digital data for the safety of air navigation and for the regular, efficient and economic operation of air traffic 6

7 services; Air traffic service means a generic term meaning variously, flight information service, alerting service, air traffic advisory service, air traffic control service (area control service, approach control service or aerodrome control service); Aircraft address means a unique combination of 24 bits available for assignment to an aircraft for the purpose of air-ground communications, navigation and surveillance; Aircraft address means a unique combination of twenty-four bits available for assignment to an aircraft for the purpose of air-ground communications, navigation and surveillance; Aircraft data circuit-terminating equipment (ADCE) means an aircraft specific data circuit-terminating equipment that is associated with an airborne data link processor (ADLP). It operates a protocol unique to Mode S data link for data transfer between air and ground; Aircraft data link processor (ADLP) means an aircraftresident processor that is specific to a particular airground data link (e.g. Mode S) and which provides channel management, and segments and/or reassembles messages for transfer. It is connected to one side of aircraft elements common to all data link systems and on the other side to the air-ground link itself; Aircraft earth station (AES) means a mobile earth station in the aeronautical mobile-satellite service located on board an aircraft (see also GES ); Aircraft/vehicle means a machine or device capable of atmospheric flight, or a vehicle on the airport surface movement area (i.e. runways and taxiways); Aircraft means the term aircraft may be used to refer to Mode S emitters (e.g. aircraft/vehicles), where appropriate; Air-initiated protocol means a procedure initiated by a Mode S aircraft installation for delivering a standard length or extended length downlink message to the ground; air navigation service provider herein also refered to as ANSP, means independent ently established for the purpose of providing air navigation services in terms of the Civil Aviation Avt or Regulations made there under 7

8 ATN end-system means an ATN host in IPS terminology; ATN host means an ATN end-system in OSI terminology; ATN/IPS means Aeronautical Telecommunication Network/Internet Protocol Suite; Automatic dependent surveillance contract (ADS-C) means a means by which the terms of an ADS-C agreement will be exchanged between the ground system and the aircraft, via a data link, specifying under what conditions ADS-C reports would be initiated, and what data would be contained in the reports; Automatic dependent surveillance-broadcast (ADS-B) means a means by which aircraft, aerodrome vehicles and other objects can automatically transmit and/or receive data such as identification, position and additional data, as appropriate, in a broadcast mode via a data link; Automatic terminal information service (ATIS) means the automatic provision of current, routine information to arriving and departing aircraft throughout 24 hours or a specified portion thereof; BDS Comm-B Data Selector means the 8-bit BDS code determines the register whose contents are to be transferred in the MB field of a Comm-B reply. It is expressed in two groups of 4 bits each, BDS1 (most significant 4 bits) and BDS2 (least significant 4 bits); Bit error rate (BER) means the number of bit errors in a sample divided by the total number of bits in the sample, generally averaged over many such samples; Broadcast means a transmission of information relating to air navigation that is not addressed to a specific station or stations; Broadcast means the protocol within the Mode S system that permits uplink messages to be sent to all aircraft in coverage area, and downlink messages to be made available to all interrogators that have the aircraft wishing to send the message under surveillance; Burst means a time-defined, contiguous set of one or more related signal units which may convey user information and protocols, signalling, and any necessary preamble.; Capability report means information identifying whether the transponder has a data link capability as reported in the capability (CA) field of an all-call reply or squitter 8

9 transmission (see data link capability report ); Carrier-to-multipath ratio (C/M) means the ratio of the carrier power received directly, i.e. without reflection, to the multipath power, i.e. carrier power received via reflection; Carrier-to-noise density ratio (C/No) means the ratio of the total carrier power to the average noise power in a 1 Hz bandwidth, usually expressed in dbhz; channel rate accuracy means this is relative accuracy of the clock to which the transmitted channel bits are synchronized. For example, at a channel rate of 1.2 kbits/s, maximum error of one part in 106 implies the maximum allowed error in the clock is ± Hz; channel rate means the rate at which bits are transmitted over the RF channel. These bits include those bits used for framing and error correction, as well as the information bits. For burst transmission, the channel rate refers to the instantaneous burst rate over the period of the burst; circuit mode means a configuration of the communications network which gives the appearance to the application of a dedicated transmission path; close-out means a command from a Mode S interrogator that terminates a Mode S link layer communication transaction; cluster of interrogators means two or more interrogators with the same interrogator identifier (II) code, operating cooperatively to ensure that there is no interference to the required surveillance and data link performance of each of the interrogators, in areas of common coverage; coded chip means a 1 or 0 output of the rate ½ or ¼ convolutional code encoder; Comm-A means a 112-bit interrogation containing the 56-bit MA message field. This field is used by the uplink standard length message (SLM) and broadcast protocols; Comm-B means a 112-bit reply containing the 56-bit MB message field. This field is used by the downlink SLM, ground-initiated and broadcast protocols; Comm-C means a 112-bit interrogation containing the 80-bit MC message field. This field is used by the uplink extended length message (ELM) protocol; 9

10 Comm-D means a 112-bit reply containing the 80-bit MD message field. This field is used by the downlink ELM protocol; Connection establishment delay means connection establishment delay, as defined in ISO 8348, includes a component, attributable to the called subnetwork (SN) service user, which is the time between the SN- CONNECT indication and the SN-CONNECT response. This user component is due to actions outside the boundaries of the satellite subnetwork and is therefore excluded from the AMS(R)S specifications; connection means a logical association between peer-level entities in a communication system; Controller Pilot Data Link Communications (CPDLC) means a means of communication between controller and pilot, using data link for ATC communications; CNS means communication, navigation and surveillance; COSPAS-SARSAT means Space System for Search of vessels in distress) (Search and Rescue Satellite- Aided Tracking); current slot means the slot in which a received transmission begins; Data Circuit-Terminating Equipment (DCE) means a DCE is a network provider equipment used to facilitate communications between DTEs; Data Link Capability Report means information in a Comm- B reply identifying the complete Mode S communications capabilities of the aircraft installation; Data Link Entity (DLE) means a protocol State machine capable of setting up and managing a single data link connection; Data Link Flight Information Services (D-FIS) means the provision of FIS via data link; Data Link Service (DLS) sublayer means the sublayer that resides above the MAC sublayer, for VDL Mode 4, the DLS sublayer resides above the VSS sublayer, and the DLS manages the transmit queue, creates and destroys DLEs for connection oriented communications, provides facilities for the LME to manage the DLS, and provides facilities for connectionless communications; Data Link-Automatic Terminal Information service (D-ATIS) 10

11 means the provision of ATIS via data link; Data Signalling Rate means data signalling rate refers to the passage of information per unit of time, and is expressed in bits/second. Data signalling rate is given by the formula: where m is the number of parallel channels, Ti is the minimum interval for the ith channel expressed in seconds, ni is the number of significant conditions of the modulation in the ith channel; Data Terminal Equipment (DTE) means a DTE is an endpoint of a subnetwork connection; Data Transfer Delay (95th percentile) means the 95th percentile of the statistical distribution of delays for which transit delay is the average; Data Transit Delay means in accordance with ISO 8348, the average value of the statistical distribution of data delays whichrepresent the subnetwork delay and does not include the connection establishment delay; Degree of Standardized Test Distortion means the degree of distortion of the restitution measured during a specific period of time when the modulation is perfect and corresponds to a specific text; Designated Operational Coverage (DOC) area means the area in which a particular service is provided and in which the service is afforded frequency protection; Direct Link Service (DLS) means a data communications service which makes no attempt to automatically correct errors, detected or undetected, at the link layer of the air-ground communications path (Error control may be effected by end-user systems); doppler shift means the frequency shift observed at a receiver due to any relative motion between transmitter and receiver; Downlink ELM (DELM) means extended length downlink communication by means of 112-bit Mode S Comm-D replies, each containing the 80-bit Comm-D message field (MD); downlink means a term referring to the transmission of data from an aircraft to the ground with Mode S air-to- 11

12 ground signals being transmitted on the MHz reply frequency channel; effective margin means that margin of an individual apparatus which could be measured under actual operating conditions; end-to-end means pertaining or relating to an entire communication path, typically from the interface between the information source and the communication system at the transmitting end to the interface between the communication system and the information user or processor or application at the receiving end; end-user means an ultimate source and/or consumer of information; Energy per symbol to noise density ratio (Es/No) means the ratio of the average energy transmitted per channel symbol to the average noise power in a 1 Hz bandwidth, usually expressed in db. For A-BPSK and A-QPSK, one channel symbol refers to one channel bit; Equivalent isotropically radiated power (E.I.R.P.) means the product of the power supplied to the antenna and the antenna gain in a given direction relative to an isotropic antenna (absolute or isotropic gain); Extended Golay Code means an error correction code capable of correcting multiple bit errors; Extended length message (ELM) means a series of Comm-C interrogations (uplink ELM) transmitted without the requirement for intervening replies, or a series of Comm-D replies (downlink ELM) transmitted without intervening interrogations; Flight information service (FIS) means a service provided for the purpose of giving advice and information useful for the safe and efficient conduct of flights; Forward error correction (FEC) means the process of adding redundant information to the transmitted signal in a manner which allows correction, at the receiver, of errors incurred in the transmission; frame means the link layer frame is composed of a sequence of address, control, FCS and information fields. For VDL Mode 2, these fields are bracketed by opening and closing flag sequences, and a frame may or may not include a variable-length information field. 12

13 frame means the basic unit of transfer at the link level. In the context of Mode S subnetwork, a frame can include from one to four Comm-A or Comm-B segments, from two to sixteen Comm-C segments, or from one to sixteen Comm-D segments; Gain-to-noise temperature ratio means the ratio, usually expressed in db/k, of the antenna gain to the noise at the receiver output of the antenna subsystem. The noise is expressed as the temperature that a 1 ohm resistor must be raised to produce the same noise power density; Gaussian filtered frequency shift keying (GFSK) means a continuous-phase, frequency shift keying technique using two tones and a Gaussian pulse shape filter. General formattermanager (GFM) means the aircraft function responsible for formatting messages to be inserted in the transponder registers. It is also responsible for detecting and handling error conditions such as the loss of input data; Global signalling channel (GSC) means a channel available on a worldwide basis which provides for communication control; Ground data circuit-terminating equipment (GDCE) means a ground specific data circuit-terminating equipment associated with a ground data link processor (GDLP). It operates a protocol unique to Mode S data link for data transfer between air and ground; Ground data link processor (GDLP) means a ground-resident processor that is specific to a particular air-ground data link, such as Mode S, and which provides channel management, and segments or reassembles messages for transfer andis connected on one side by means of its DCE to ground elements common to all data link systems, and on the other side to the air-ground link itself; Ground earth station (GES) means an earth station in the fixed satellite service, or, in some cases, in the aeronautical mobile-satellite service, located at a specified fixed point on land to provide a feeder link for the aeronautical mobile satellite service; Ground-initiated Comm-B (GICB) means the ground- 13

14 initiated Comm-B protocol allows the interrogator to extract Comm-B replies containing data from a defined source in the MB field; Ground-initiated protocol menas a procedure initiated by a Mode S interrogator for delivering standard length or extended length messages to a Mode S aircraft installation; HFDL means High Frequency Data Link; HFNPDU means High frequency network protocol data unit; High frequency network protocol data unit means user data packet; High performance receiver means a UAT receiver with enhanced selectivity to further improve the rejection of adjacent frequency DME interference; ISO/IEC means international standards and Telecommunication Standardization Sector of the International Telecommunications Union recommendations; Link layer means the layerthat- (a) lies immediately above the physical layer in the Open Systems Interconnection protocol model; (b) provides for the reliable transfer of information across the physical media; and (c) subdivided into the data link sublayer and the media access control sublayer; Link management entity (LME) means a protocol State machine - (a) that is capable of acquiring, establishing and maintaining a connection to a single peer system; (b) that is establishing data link and subnetwork connections, hands-off those connections, and manages the media access control sublayer and physical layer; (c) that tracks how well it can communicate with the ground stations of a single ground system; (d) fom which an aircraft VME instantiates an LME for each ground station that it monitors and similarly, the ground VME instantiates an LME for each aircraft that it monitors; and (e) that is deleted when communication with the peer system is no longer viable; 14

15 Link protocol data unit (LPDU means data unit which encapsulates a segment of an HFNPDU; Link means a link that connects an aircraft DLE and a ground DLE and is uniquely specified by the combination of aircraft DLS address, the ground DLS address and adifferent subnetwork entity resides above every link endpoint. Low modulation rates means modulation rates up to and including 300 bauds; M burst means a management channel data block of bits used in VDL Mode 3 whose burst contains signalling information needed for media access and link status monitoring; Manual of ANS Standards (MANSOPS) means a manual developed by the Authority prescribing the standards and recommended practices applicable to the provision of air navigation services Margin means the maximum degree of distortion of the circuit at the end of which the apparatus is situated which is compatible with the correct translation of all the signals which it may possibly receive; M-ary phase shift keying (M-PSK) modulation means a digital phase modulation that causes the phase of the carrier waveform to take on one of a set of M values; Media access control (MAC) means the sublayer that acquires the data path and controls the movement of bits over the data path; Media access protocol data unit (MPDU) means data unit which encapsulates one or more LPDUs; Medium modulation rates means modulation rates above 300 and up to and including bauds; Mode 2 means a data-only VDL mode that uses D8PSK modulation and a carrier sense multiple access (CSMA) control scheme; Mode 3 means a voice and data VDL mode that uses D8PSK modulation and a TDMA media access control scheme; Mode 4 means a data-only VDL mode using a GFSK modulation scheme and self-organizing time division multiple access (STDMA); Mode S air-initiated Comm-B (AICB) protocol means a procedure initiated by a Mode S transponder for 15

16 transmitting a single Comm-B segment from the aircraft installation; Mode S broadcast protocols means procedures allowing standard length uplink or downlink messages to be received by more than one transponder or ground interrogator respectively; Mode S ground-initiated Comm-B (GICB) protocol means a procedure initiated by a Mode S interrogator for eliciting a single Comm-B segment from a Mode S aircraft installation, incorporating the contents of one of 255 Comm-B registers within the Mode S transponder; Mode S multisite-directed protocol means a procedure to ensure that extraction and close-out of a downlink standard length or extended length message is affected only by the particular Mode S interrogator selected by the aircraft; Mode S packet means a packet conforming to the Mode S subnetwork standard, designed to minimize the bandwidth required from the air-ground link. ISO 8208 packets may be transformed into Mode S packets and vice-versa; Mode S specific protocol (MSP) means a protocol that provides restricted datagram service within the Mode S subnetwork; Mode S specific services entity (SSE) means an entity resident within an XDLP to provide access to the Mode S specific services; Mode S specific services means a set of communication services provided by the Mode S system which are not available from other air-ground subnetworks, and therefore not interoperable; Mode S subnetwork means a means of performing an interchange of digital data through the use of secondary surveillance radar (SSR) Mode S interrogators and transponders in accordance with defined protocols; Modulation rate means the reciprocal of the unit interval measured in seconds. This rate is expressed in bauds; M-PSK symbol means one of the M possible phase shifts of the M-PSK modulated carrier representing a group of log2 M coded chips; Network (N) means the word network and its abbreviation 16

17 N in ISO 8348 are replaced by the word subnetwork and its abbreviation SN, respectively, wherever they appear in relation to the subnetwork layer packet data performance; Optimum sampling point means the optimum sampling point of a received UAT bit stream is at the nominal centre of each bit period, when the frequency offset is either plus or minus khz. Packet means the basic unit of data transfer among communication devices within the network layer such as an ISO 8208 packet or a Mode S packet; Peak envelope power (PEP) means the peak power of the modulated signal supplied by the transmitter to the antenna transmission line; Physical layer protocol data unit (PPDU) means data unit passed to the physical layer for transmission, or decoded by the physical layer after reception; Physical layer means the lowest level layer in the Open Systems Interconnection protocol model. The physical layer is concerned with the transmission of binary information over the physical medium such as VHF radio; Point-to-point means, pertaining or relating to the interconnection of two devices, particularly end-user instruments, a communication path of service intended to connect two discrete end-users, as distinguished from broadcast or multipoint service; Power measurement point (PMP) means: a cable that connects the antenna to the UAT equipment and the PMP is the end of that cable that attaches to the antenna. All power measurements are considered as being made at the PMP unless otherwise specified. The cable connecting the UAT equipment to the antenna is assumed to have 3 db of loss. Pseudorandom message data block means several UAT requirements State that performance will be tested using pseudorandom message data blocks. Pseudorandom message data blocks should have statistical properties that are nearly indistinguishable from those of a true random selection of bits. For instance, each bit should have (nearly) equal probability 17

18 of being a ONE or a ZERO, independent of its neighbouring bits. There should be a large number of such pseudorandom message data blocks for each message type (Basic ADS-B, Long ADS-B or Ground Uplink) to provide sufficient independent data for statistical performance measurements. See Section 2.3 of Part I of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) for an example of how to provide suitable pseudorandom message data blocks. Quality of service (QOS) means the information relating to data transfer characteristics used by various communications protocols to achieve various levels of performance for network users; Quality of service means the information relating to data transfer characteristics used by various communication protocols to achieve various levels of performance for network users; Reed-Solomon code means an error correction code capable of correcting symbol errors which arecollections of bits, these codes provide good burst error correction capabilities; Reliable link service (RLS) means a data communications service provided by the subnetwork which automatically provides for error control over its link through error detection and requested retransmission of signal units found to be in error; Residual error rate means the ratio of incorrect, lost and duplicate subnetwork service data units (SNSDUs) to the total number of SNSDUs that were sent; Segment means a portion of a message that can be accommodated within a single MA/MB field in the case of a standard length message, or MC/MD field in the case of an extended length message. This term is also applied to the Mode S transmissions containing these fields; SELCAL means selective calling; Self-organizing time division multiple access (STDMA) means a multiple access scheme based on time-shared use of a radio frequency (RF) channel employingdiscrete contiguous time slots as the fundamental shared resource and a set of operating 18

19 protocols that allows users to mediate access to these time slots without reliance on a master control station; Service volume means a part of the facility coverage where the facility provides a particular service in accordance with relevant SARPs and within which the facility is afforded frequency protection; Slot means one of a series of consecutive time intervals of equal duration with each burst transmission starting at the beginning of a slot; Slotted aloh means a random access strategy whereby multiple users access the same communications channel independently, but each communication must be confined to a fixed time slot and the same timing slot structure is known to all users, but there is no other coordination between the users; Spot beam means satellite antenna directivity whose main lobe encompasses significantly less than the earth s surface that is within line-of-sight view of the satellitewhich may be designed so as to improve system resource efficiency with respect to geographical distribution of user earth stations; Squitter protocol data unit (SPDU) means data packet which is broadcast every 32 seconds by an HFDL ground station on each of its operating frequencies, and which contains link management information; Standard length message (SLM) means an exchange of digital data using selectively addressed Comm-A interrogations and/or Comm-B replies (see Comm-A and Comm-B ); Standard UAT receiver means a general purpose UAT receiver satisfying the minimum rejection requirements of interference from adjacent frequency distance measuring equipment (DME); Sub network service data unit (SNSDU) means an amount of sub network user data, the identity of which is preserved from one end of a sub network connection to the other; Subnetwork connection means a long-term association between an aircraft DTE and a ground DTE using successive virtual calls to maintain context across link handoff; 19

20 Subnetwork dependent convergence function (SNDCF) means a function that matches the characteristics and services of a particular subnetwork to those characteristics and services required by the internetwork facility; Subnetwork entity means, the phrase ground DCE will be used for the subnetwork entity in a ground station communicating with an aircraft; the phrase ground DTE will be used for the subnetwork entity in a ground router communicating with an aircraft station; and, the phrase aircraft DTE is used for the subnetwork entity in an aircraft communicating with the station. A subnetwork entity is a packet layer entity as defined in ISO 8208; Subnetwork layer means the layer that establishes, manages and terminates connections across a subnetwork; Subnetwork management entity (SNME) means an entity resident within a GDLP that performs subnetwork management and communicates with peer entities in intermediate or end-systems; Subnetwork means an actual implementation of a data network that employs a homogeneous protocol and addressing plan, and is under the control of a single authority; Successful message reception (SMR) means the function within the UAT receiver for declaring a received message as valid for passing to an application that uses received UAT messages; See Section 4 of Part I of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) for a detailed description of the procedure to be used by the UAT receiver for declaring successful message reception; SVC means switched virtual circuits; Synchronous Operation means operation in which the time interval between code units is a constant; System means: a VDL-capable entity system comprising of one or more stations, as well the associated VDL management entity, A system may either be an aircraft system or a ground system; Time Division Multiple Access (TDMA) means a multiple access scheme based on time-shared use of an RF 20

21 channel employing: (1)discrete contiguous time slots as the fundamental shared resource; and (2) a set of operating protocols that allows users to interact with a master control station to mediate access to the channel; Time Division Multiple Access (TDMA) means a multiple access scheme based on time-shared use of an RF channel employing- (a) discrete contiguous time slots as the fundamental shared resource; and (b) a set of operating protocols that allows users to interact with a master control station to mediate access to the channel; Time Division multiplex (TDM) means a channel sharing strategy in which packets of information from the same source but with different destinations are sequenced in time on the same channel; timeout means the cancellation of a transaction after one of the participating entities has failed to provide a required response within a pre-defined period of time; total voice transfer delay means the elapsed time commencing at the instant that speech is presented to the AES or GES and concluding at the instant that the speech enters the interconnecting network of the counterpart GES or AES. This delay includes vocoder processing time, physical layer delay, RF propagation delay and any other delays within an AMS(R)S sub network; Transit delay means in packet data systems, the elapsed time between a request to transmit an assembled data packet and an indication at the receiving end that the corresponding packet has been received and is ready to be used or forwarded; UAT ADS-B message means a message broadcasted once per second by each aircraft to convey State vector and other information. UAT ADS-B messages can be in one of two forms depending on the amount of information to be transmitted in a given second: the Basic UAT ADS- B Message or the Long UAT ADS-B Message (see for definition of each). UAT ground stations can support traffic information service-broadcast (TIS- B) through transmission of individual ADS-B messages 21

22 in the ADS-B segment of the UAT frame; UAT ground uplink message means a message broadcasted by ground stations, within the ground segment of the UAT frame, to convey flight information such as text and graphical weather data, advisories, and other aeronautical information, to aircraft that are in the service volume of the ground station (see for further details); Universal Access Transceiver (UAT) means a broadcast data link operating on 978 MHz, with a modulation rate of Mbps; Uplink ELM (UELM) means extended length uplink communication by means of 112-bit Mode S Comm-C interrogations, each containing the 80-bit Comm-C message field (MC); Uplink means a term referring to the transmission of data from the ground to an aircraft. Mode S ground-to-air signals are transmitted on the MHz interrogation frequency channel; UTC means Coordinated Universal Time; User group means a group of ground and/or aircraft stations which share voice and/or data connectivity. For voice communications, all members of a user group can access all communications. For data, communications include point-to-point connectivity for air-to-ground messages, and point-to-point and broadcast connectivity for ground-to-air messages; VDL means VHF Digital Link; VDL Management Entity (VME) means a VDL-specific entity that provides the quality of service requested by the ATN-defined SN_SME. A VME uses the LMEs (that it creates and destroys) to enquire the quality of service available from peer systems; VDL Mode 4 burst means a VHF digital link (VDL) Mode 4 burst is composed of a sequence of source address, burst ID, information, slot reservation and frame check sequence (FCS) fields, bracketed by opening and closing flag sequences; VDL Mode 4 DLS system means a VDL system that implements the VDL Mode 4 DLS and subnetwork protocols to carry ATN packets or other packets; 22

23 VDL Mode 4 specific services (VSS) sub-layer means the sublayer that resides above the MAC sublayer and provides VDL Mode 4 specific access protocols including reserved, random and fixed protocols; VDL station means an aircraft-based or ground-based physical entity, capable of VDL Mode 2, 3 or 4; VHF means Very High Frequency; VHF Digital Link (VDL) means a constituent mobile subnetwork of the aeronautical telecommunication network (ATN), operating in the aeronautical mobile VHF frequency band. In addition, the VDL may provide non-atn functions such as, for instance, digitized voice vocoder means a low bit rate voice encoder or decoder; voice unit means device that provides a simplex audio and signalling interface between the user and VDL; Voice-Automatic Terminal Information Service (Voice- ATIS) means the provision of ATIS by means of continuous and repetitive voice broadcasts; VSS user means a user of the VDL Mode 4 specific services. The VSS user could be higher layers in the VDL Mode 4 SARPs or an external application using VDL Mode 4; XDCE means a general term referring to both the ADCE and the GDCE; and XDLP means a general term referring to both the ADLP and the GDLP. Application 3. These Regulations shall apply to the provision of Communication, Navigation and Surveillance Services within designated air spaces and at aerodromes. PART II GENERAL REQUIREMENTS Requirements for Communicatio, Navigation and Surveillance facilities Certification of Communicatio, Navigation and 4. The minimum requirements for installation, commissioning, operation and maintenance of the Communication, Navigation and Surveillance (CNS) facilities shall conform to these Regulations. 5. A person who wishes to provide Communication, Navigation and Surveillance service or operate a facility to 23

24 Surveillance Service Provider support an air traffic service shall have an ANSP certificate in accordance with the Civil Aviation (Air Navigation Services) Regulations Approval Requirement Inspections and Audits Siting and Installation Commissio-ning Requirement 6.-(1) A person shall not provide communication, navigation and surveillance systems or operate communication, navigation and surveillance facility or facilities in the designated airspace and aerodromes unless the system or facility has been approved by the Authority. (2) The Authority shall approve installation, use, decommissioning, upgrading or relocation of all the communication, navigation and surveillance facility or facilities in the designated airspace and aerodromes. 7.-(1) The authority shall carry out safety inspections and audits on Communication, Navigation and Surveillance facilities, documents and records of the Communication, Navigation and Surveillance facilities to determine compliance in accordance with these Regulations. (2) An inspector of the authority shall have unrestricted access to the facilities, installations, records and documents of the service provider to determine compliance of these regulations. 8.-(1) The ANSP shall determine the site for installation of a new facility based on operational requirements, construction aspects and maintainability (2) The facility in sub-regulation (1) shall be installed by maintenance personnel who are fully qualified in air navigation facilities and who have knowledge of the operations, testing, and maintenance of the Communication, Navigation and Surveillance facilities. 9.-(1) Communication, Navigation and Surveillance facilities shall be confirmed during commissioning and subsequent maintenance that the facility achieves and continues to meet the standard operating parameters and applicable figures recorded. (2) The ANSP shall: (a) establish procedures to ensure that each new facility is commissioned to meet the specifications for that facility and is in compliance with these 24

25 Regulations; (b) ensure that the system performance of the new facility has been validated by all necessary tests; and (c) ensure that procedures include documentation of tests conducted on the facility prior to the commissioning, including those that test the compliance of the facility with the applicable standards and any flight check required in compliance with these Regulations Availability and reliability Test Equipment Record Keeping 10.-(1) The performance of technical facilities shall be monitored, reviewed and reported in accordance with these Regulations. (2) The Communication, Navigation and Surveillance provider shall provide protected power supply system, battery back-up, reliable connectivity and air conditioning. 11.-(1) A Communication, Navigation and Surveillance provider shall: (a) ensure that appropriate tools and test equipment are available for personnel to maintain the operation of equipment; (b) establish a procedure to control, calibrate, and maintain all the equipment required; (c) use documented procedures to control, calibrate and maintain test equipment (2) The maintenance plan or the operating and maintenance instructions for each facility shall specify the test equipment requirements for all levels of operation and maintenance undertaken. shall. 12. A Communication, Navigation and Surveillance provider shall establish procedures to identify, collect, index, store, maintain, and dispose records covering- (a) the performance and maintenance history of each facility; (b) the establishment of the periodic test programmes for each facility; (c) each item of test equipment required for the 25

26 measurement of critical performance parameters; (d) each reported or detected facility malfunction; (e) each internal quality assurance review; and (f) each person who is authorised to place facilities into operational service. Documen-tation Periodic Inspection and Testing Flight Inspection, operation and the Maintenance Plan 13. A Communication, Navigation and Surveillance provider shall- (a) hold copies of relevant equipment manuals, technical standards, practices, instructions, maintenance procedures, site logbooks, and any other documentation that are necessary for the provision and operation of the facility. (b) have entries recording all occurrences and actions relating to operation, maintenance, modification, failure, faults, removal from and restoration to service in the log books. (c) establish a procedure for the control of the documentation required under sub regulation (a) above. 14.-(1) A Communication, Navigation and Surveillance provider shall establish a procedure for the periodic inspection and testing of the communication, navigation and surveillance systems to verify that each facility meets the applicable operational requirements and performance specifications for that facility. (2) Periodic inspection shall include: (a) security of the facility and site; (b) adherence to the approved maintenance programme; (c) upkeep of the equipment, building, site and site services; and (d) Adequacy of facility records and documentation. 15.-(1) A Communication, Navigation and Surveillance provider shall- (a) ensure that the radio navigation aids prescribed by the Authority are available for use by aircraft engaged in air navigation and are subjected to periodic ground and flight inspection; and 26

27 (b) establish an operation and maintenance plan for the Communication, Navigation and Surveillance facilities, to meet the safety requirements as stipulated in these Regulations. (2) The operation and maintenance plan established under sub-regulation 1 shall provide for the timely and appropriate detection and warning of system failures and degradations. Training requirements for Communicatio, Navigation And Surveillance Personnel. Commu-nicatio, Navigation And Surveillance personnel requirements 16.- Communication, Navigation and Surveillance Provider shall- (a) ensure that all its personnel possess the skills and competencies required in the provision of the Communication Navigation and Surveillance Services; (b) develop a training policy and programme for the organization; (c) maintain individual training records and plan for each of its staff; and (d) conduct periodic review of the training Plan. 17. A Communication, Navigation and Surveillance provider shall- (a) employ sufficient number of competent personnel to perform the installation, operation and maintenance of communication, navigation and surveillance system in the designated airspace and aerodromes as prescribed by the Authority; (b) provide in the MANSOPS an analysis of the personnel required to perform the Communication Navigation and surveillance services for each facility taking into account the duties and workload required; (c) not perform a function related to the installation, operation or maintenance of any communication, navigation and a surveillance system unless- (d) that person has successfully completed training in the performance of that function; (e) a Communication, Navigation and Surveillance provider is satisfied that the technical person is competent in performing that function; and 27

28 (f) that person has been certified as prescribed by the Authority. Proficiency certification program. Installation, operation and maintenance of ommuni-cation, Navigation and Surveillance systems. 18. The Authority shall develop proficiency certification program of personnel who are engaged in the installation, operation and maintenance of Communication, Navigation and Surveillance systems used in the designated airspace and aerodrome. 19. A Communication, Navigation and Surveillance provider shall establish procedure to ensure that the communication, navigation and surveillance systems- (a) are operated, maintained, available and reliable in accordance with the requirements prescribed by the Authority; (b) are designed to meet the applicable operational specification for that facility; (c) are installed and commissioned as prescribed by the Authority; and (d) conform to the applicable system characteristics and specification as prescribed in the Communication, Navigation And Surveillance Technical standards of the Authority. PART III AERONAUTICAL TELECOMMUNICATION NETWORK. Support of Aeronautical Telecommunicat ion Network Application 20.-(1) The Aeronautical Telecommunication Network shall specifically and exclusively be used to provide digital data communications services to air traffic service provider organizations and aircraft operating agencies in support of: (a) Air Traffic Services communications with aircraft; (b) Air Traffic Services Communications between air traffic service units; (c) Aeronautical Operational Control Communications; and (d) Aeronautical Administrative Communications. (2) Aeronautical Telecommunication Network communication services under sub-regulation (1) shall support Aeronautical Telecommunication Network applications. 28

29 Requirements for implementation of Aeronautical Telecommunicat ion Network 21.-(1) Requirements for implementation of the Aeronautical Telecommunication Network shall be made on the basis of regional air navigation agreements. (2) The agreements in sub-regulation (1) shall specify the area in which the communication standards for the Aeronautical Telecommunication Network or Open System Interconnection or the Aeronautical Telecommunication Network orinternet Protocol Suite are applicable. (3) The Aeronautical Telecommunication Network shall either use International Organization for Standardization, communication standards for Open Systems Interconnection or use the Internet Society communications standards for the Internet Protocol Suite. (4) The Aeronautical Fixed Telecommunication Network/ Aeronautical Message Handling System gateway shall ensure the interoperability of Aeronautical Fixed Telecommunication Network stations and networks with the Aeronautical Telecommunication Network. (5) An authorized paths for the Aeronautical Fixed Telecommunication Network shall be defined on the basis of a predefined routing policy. (6) The Aeronautical Telecommunication Network shalltransmit, relay and deliver messages in accordance with the priority classifications and without discrimination or undue delay; (a) provide means to define data communications that can be carried only over authorized paths for the traffic type and category specified by the user; (b) provide communication in accordance with the prescribed Required Communication Performance contained in Doc (c) operate in accordance with the communication priorities specified in Table 1and Table 2 as set out in First Schedule (to these Regulation); (d) enable exchange of application information when one or more authorized paths exist; (e) notify the appropriate application processes when no authorized path exists; (f) make provisions for the efficient use of limited bandwidth sub-networks; 29

30 (g) enable an aircraft intermediate system to connect to a ground intermediate system via different subnetworks; (h) enable an aircraft intermediate system to connect to different ground intermediate systems; (i) enable the exchange of address information between applications;and (j) be accurate to within one second of UTC where the absolute time of day is used. Aeronautical Telecommunicat ion Network Applications Requireme-nts Air-ground applications Ground-Ground Applications 22.-(1) The Aeronautical Telecommunication Network shall support the Data Link Initiation Capability applications when air-ground data links are implemented. (2) The Aeronautical Telecommunication Network or Open System Interconnection end-system shall support the following Directory Services application functions when Aeronautical Message Handling System and security protocols are implemented- (a) directory information retrieval; and (b) directory information modification. 23. The Aeronautical Telecommunication Network shall be capable of supporting one or more of the following applications- (a) automatic Dependent Surveillance Contract; (b) Controller Pilot Data Link Communication ; and (c) Flight Information Service including Automatic Terminal Information Service and Meteorological Reports. 24. The Aeronautical Telecommunication Network shall be capable of supporting the following applications- (a) Air Traffic Service Interfacility Data Communication; and (b) Air Traffic Service Message Handling Services applications. PART IV AERONAUTICAL TELECOMMUNICATION NETWORK COMMUNICATIONS SERVICE REQUIREMENTS 30

31 ATN Protocol Suite upper layer communications service 25. An Aeronautical Telecommunication Network host shall be capable of supporting the Aeronautical Telecommunication Network or Internet Protocol Suite upper layers including an application layer. ATN /Open System Interconnection upper layer communications service ATN /Internet Protocol Suite communications service ATN/Open System Interconnection communications service 26. An Aeronautical Telecommunication Network or Open System Interconnection end-system shall be capable of supporting the Open System Interconnection Upper Layer Communications Service including session, presentation and application layers. 27.-(1) An Aeronautical Telecommunication Network host shall be capable of supporting the Aeronautical Telecommunication Network or Internet Protocol Suite including- (a) transport layer in accordance with Transmission Control Protocols and User Datagram Protocols; and (b) network layer in accordance with Internet Protocol version 6. (2) An Internet Protocol Suite router shall support the Aeronautical Telecommunication Network layer in accordance with Internet Protocol version 6 and multiprotocol extensions. 28.-(1) An Aeronautical Telecommunication Network or Open System Interconnection end-system shall be capable of supporting the Aeronautical Telecommunication Network including the - (a) transport layer in accordance with International Organization for Standardization Transport Protocol Class 4 and optionally Connectionless Transport Protocol; and (b) network layer in accordance with International Organization for Standardization, Connectionless Network Protocol. (2) An ATN Intermediate System shall support the Aeronautical Telecommunication Network layer in accordance with International Organization for Standardization, Connectionless Network Protocol and International Organization for Standardization, Inter-domain routing protocol. 31

32 ATN Naming And Addressing Requirements ATN security requirements Aeronautical Mobile-Satellite (Route) Service 29.-(1) The Aeronautical Telecommunication Network shall provide provisions for unambiguous application identification and addressing. (2) The Aeronautical Telecommunication Network shall provide means to unambiguously address all Aeronautical Telecommunication Network end-systems and intermediate systems. (3) The Aeronautical Telecommunication Network addressing and naming plans shall allow the Authority and Organizations to assign addresses and names within their own administrative domains. 30.-(1) The Aeronautical Telecommunication Network shall- (a) make provisions whereby only the controlling Air Traffic Services unit may provide Air Traffic Control instructions to aircraft operating in its airspace; (b) enable the recipient of a message to identify the originator of that message; and (c) be protected against service attacks to a level consistent with the application service requirements. (2) Aeronautical Telecommunication Network endsystems supporting Aeronautical Telecommunication Network security services shall be capable of authenticating the identity of peer end-systems, authenticating the source of messages and ensuring the data integrity of the messages. 31.-(1) A mobile-satellite system intended to provide Aeronautical Mobile-Satellite (Route) Service shall conform to the requirements of these Regulations. (2) An Aeronautical Mobile-Satellite (Route) Service AMS(R)s system shall support packet data service, voice service or both. (3) Requirements for mandatory carriage of AMS(R)s system equipment including the level of system capability shall be made on the basis of regional air navigation agreements which specify the airspace of operation and the implementation timescales for the carriage of equipment and the level of system 32

33 capability shall include the performance of the Aircraft Earth Station, the satellite and the Ground Earth Station. (4) The agreements specified in sub regulation (3) shall provide at least a notice of two years of mandatory carriage of airborne systems. (5) The Authority shall coordinate with national authorities and service providers the implementation aspects of an Aeronautical Mobile-Satellite (Route) Service system that permit worldwide interoperability and optimum use, as appropriate. RF Characteristics Priority and preemptive access 32.-(1) When providing Aeronautical Mobile-Satellite (Route) Service communications, an Aeronautical Mobile- Satellite (Route) Service system shall operate only in frequency bands which are appropriately allocated to Aeronautical Mobile-Satellite (Route) Service and protected by the International Telecommunications Union Radio Regulations. (2) The total emissions of the Aircraft Earth Station necessary to meet designed system performance shall be controlled to avoid harmful interference to other systems necessary to support safety and regularity of air navigation, installed on the same or other aircraft. (3) Emissions from an Aeronautical Mobile-Satellite (Route) Service system Aircraft Earth Station shall not cause harmful interference to an Aircraft Earth Station providing Aeronautical Mobile-Satellite (Route) Serviceon a different aircraft. (4) The Aircraft Earth Station equipment shall operate properly in an interference environment causing a cumulative relative change in its receiver noise temperature (ΔT/T) of 25 per cent. 33.-(1) Every aircraft earth station and ground earth station shall be designed to ensure that messages transmitted in accordance with Civil Aviation (Communication Procedures) Regulations including their order of priority, are not delayed by the transmission and reception of other types of messages. (2) As a means to comply with the sub regulation (1) message types not defined in the Civil Aviation (Communication Procedures) Regulations shall be terminated 33

34 even without warning, to allow messages specified in the Civil Aviation (Communication Procedures) Regulations to be transmitted and received. (3) All Aeronautical Mobile-Satellite (Route) Service data packets and all Aeronautical Mobile-Satellite (Route) Service voice calls shall be identified as to their associated priority. (4) The system shall provide voice communications priority over data communications within the same message category. Signal acquisition and tracking 34. The Aircraft Earth Station, Ground Earth Station and satellites shall properly acquire and track service link signals when the- (a) aircraft is moving at a ground speed of up to km/h (800 knots) along any heading; and (b) component of the aircraft acceleration vector in the plane of the satellite orbit is up to 0.6 g. PART V PERFORMANCE REQUIREMENTS Designated operational coverage and failure notification AES requirements 35. An Aeronautical Mobile-Satellite (Route) Service system shall- (a) provide Aeronautical Mobile-Satellite (Route) Service throughout its designated operational coverage; (b) provide timely predictions of the time, location and duration of any resultant outages until full service is restored in the event of a service failure; and (c) annunciate a loss of communications capability within 30 seconds of the time when it detects such a loss. 36. The Aircraft Earth Station shall meet the relevant performance requirements specified in regulations 18 and 19 for aircraft- (a) in straight and level flight throughout the designated operational coverage of the satellite system; or (b) attitudes of +20/-5 degrees of pitch and +/-25 34

35 degrees of roll throughout the Designated Operational Coverage of the satellite system. Packet data service performance Delay Parameters 37. Where an Aeronautical Mobile-Satellite (Route) Service system provides packet data service, it shall be capable of operating as a constituent mobile sub network of the Aeronautical Telecommunication Network. 38.-(1) Connection establishment delay shall not be greater than 70 seconds. (2) Data transit delay- (a) values shall be based on a fixed sub-network service data unit length of 128 octets in accordance with ISO 8348 and shall be defined as average values; (b) from aircraft shall not be greater than: (i) 40 seconds for the highest priority data service; (ii) 28 seconds for the lowest priority data service; (c) to aircraft shall not be greater than 12 seconds for the highest priority data service; (d) aircraft shall not be greater than 28 seconds for the lowest priority data service; (e) (95th percentile), shall not be greater than 80 seconds for the highest priority data service; (f) (95th percentile) from-aircraft, shall not be greater than 60 seconds for the lowest priority data service; (g) (95th percentile) to-aircraft shall not be greater than 15 seconds for the highest priority data service; (h) (95th percentile) to-aircraft shall not be greater than 30 seconds for the lowest priority data service; (i) (95th percentile) shall not be greater than 30 seconds in either direction Integrity 39.-(1) The residual error rate-. (a) in the from the-aircraft direction shall not be greater than 10-4 per sub-network service data unit; and (b) in the to-aircraft direction shall not be greater than 10-6 per sub-network service data unit (2) The probability of a Sub Network Connection 35

36 provider-invoked Sub Network Connection release shall not be greater than 10-4 over any one-hour interval. (3) The probability of a sub-network connection provider-invoked reset shall not be greater than 10-1 over any one-hour interval. Voice service performance Call Processing Delay Voice Quality Voice capacity, security, system interfaces, 40. The system that provides Aeronautical Mobile- Satellite (Route) Service voice service shall meet the requirements in regulations 41, 42 and (1) The 95th percentile of the time delay for: (a) a GES to present a call origination event to the terrestrial network interworking interface after a call origination event has arrived at the AES interface shall not be greater than 20 seconds; and (b) an AES to present a call origination event at its aircraft interface after a call origination event has arrived at the terrestrial network interworking interface shall not be greater than 20 seconds. 42.-(1) The voice transmission shall provide overall intelligibility performance suitable for the intended operational and ambient noise environment. (2) The total allowable transfer delay within an Aeronautical Mobile-Satellite (Route) Service sub network shall not be greater than seconds. 43. A Aeronautical Mobile-Satellite (Route) Service system shall- (a) have sufficient available voice traffic channel resources such that an Aircraft Earth Station- or Ground Earth Station originated Aeronautical Mobile-Satellite (Route) Service voice call presented to the system shall experience a probability of blockage of no more than 10-2 ; (b) provide features for the protection: (i) (ii) of messages in transit from tampering; against denial of service, degraded performance characteristics, or reduction of system capacity when subjected to external attacks; and 36

37 (iii) unauthorized entry; and (c) allow sub-network users to address Aeronautical Mobile-Satellite (Route) Service communications to specific aircraft by means of the ICAO 24-bit aircraft address. Packet data service interfaces 44. A system that provides Aeronautical Mobile- Satellite (Route) Service packet data service shall provide- (a) an interface to the Aeronautical Telecommunication Network ; and (b) a Connectivity Notification function. PART VI SECONDARY SURVEILLANCE RADAR MODE S AIR-GROUND DATA LINK Air Ground Data Link Communication 45. Where air ground data link communication is used by the Secondary Survillance Radar Mode S, the following shall be implemented; (a) the Mode S characteristics shall be as specified in Second Schedule to these Regualtions. (b) the DCE and XDCE state tables shall be as specified in the Third Schedule to these Regualtions. (c) the Mode S packet formats shall be as specified in the Fourth Schedule to these Regualtions. PART VII VERY HIGH FREQUENCY AIR-GROUND DIGITAL LINK (VDL) Radio channels and functional channels 46.-(1) An aircraft station- (a) shall be capable of tuning to any of the channels in the range specified in regulation 52 within 100 milliseconds after the receipt of an auto-tune command; and (b) for VDL Mode 3, shall be able to tune to any channel in the range specified in regulation 52 within 100 milliseconds after the receipt of any tuning command. (2) A ground station shall be capable of operating on its assigned channel within the radio frequency range detailed in 37

38 regulation 52. (3) Frequency MHz shall be reserved as a worldwide common signalling channel for VHF Air-Ground Digital Link Mode 2. System Capabilities Air-ground VHF digital link communications system characteristics System characteristics of the ground and aircraft installations for VHF Air- Ground Digital Link. 47. The VHF Air-Ground Digital Link: (a) system shall provide code-independent and byteindependent transfer of data; (b) system shall provide link layer data broadcast services Mode 2 or voice and data broadcast services Mode 3; (c) in the case of Mode 3, the data broadcast service shall support network multicasting capability originating from the ground; (d) system shall establish and maintain a reliable communications path between the aircraft and the ground system while allowing but not requiring manual intervention; (e) equipped aircraft shall transition from one ground station to another when circumstances dictate; and (f) Mode 3 system shall support a transparent, simplex voice operation based on a Listen-Before-Push- To-Talk channel access. 48.-(1) The radio frequencies used for Air-ground VHF digital link communications shall be selected from the radio frequencies in the band MHz. (2) The lowest assignable frequency used for Airground VHF digital link communications shall be MHz, and the highest assignable frequency shall be MHz and the separation between assignable frequencies shall be 25 khz. (3) The design polarization of emissions shall be vertical. 49. The VHF Air ground Digital link system characteristics for ground and aircraft installations shall be as specified in the Fifth and Sixth Schedules to these Regulations. 38

39 Physical Layer Protocols and services Link Layer Protocols and services and Sub-network Layer Protocols and services The VDL Mobile Sub Network Dependent Convergence Function VDL Mode 3 Sub Network Dependent Convergence Function. Voice Unit for Mode 3 Services 50. The VHF Air ground Digital Link systems physical layer protocols and services shall- (a) be as specified in the Seventh Schedule to these Regualtions for aircraft and ground stations; and (b) be as specified in the Tenth Schedule to these Regualtions for both mobile and ground stations of Mode 4 unless otherwise stated. 51. The VHF Air ground Digital Link systems link-. (a) layer protocols and services shall be as specified in the Eighth Schedule to these Regulations; and (b) systems sub-network layer protocols and services shall be as specified in the Ninth Schedule to these Regulations. 52.-(1) The VDL Mode 2 mobile Sub Network Dependent Convergence Function shall-. (a) be the standard mobile Sub Network Dependent Convergence Function; (b) support maintaining context across sub network calls; (c) use the same context across all Switched Virtual Circuits, (SVCs) negotiated to a Data Terminal Equipment,(DTE), when negotiated with the same parameters; or (d) support at least 2 SVCs sharing a context. 53. The VDL Mode 3 shall support -. (a) the standard International Organization for Standardization, ISO 8208 Sub Network Dependent Convergence Function as defined in ICAO Doc 9705; and (b) the denoted frame-based Sub Network Dependent Convergence Function. 54.-(1) The voice unit shall provide for a simplex, push-to-talk audio and signalling interface between the user and the VDL and two separate mutually exclusive voice circuit types shall be supported. (2) The two separate mutually exclusive voice circuit 39

40 types in sub regulation (1) are- (a) dedicated circuits; and (b) demand assigned circuits. (3) Dedicated circuits in sub regulation (2)(a) shall provide service to a specific user group on an exclusive basis with no sharing of the circuit with other users outside the group and access shall be based on a listen-before-push-to-talk discipline. (4) Demand assigned circuits in sub regulation (2) shall provide voice circuit access which is arbitrated by the ground station in response to an access request received from the aircraft station and allow dynamic sharing of the channel resource increasing trunking efficiency. (5) The voice unit operation shall support a priority override access for authorized ground users. (6) The voice unit operation shall support notification to the user of the source of a received message. (7) The voice unit shall support a coded squelch operation that offers some degree of rejection of undesired cochannel voice messages based on the burst time of arrival. Voice Unit for Mode 3 speech encoding, parameters and procedures. VDL Mode 4 radio channels VDL Mode 4 System capabilities 55. The VDL Mode 3 shall use the Advanced Multi- Band Excitation, AMBE 4.8 kbits/s encoding or decoding algorithm, version number AMBE-ATC-10, developed by Digital Voice Systems, Incorporated for voice communications. 56.-(1) A VDL Mode 4 transmitter or receiver shall be capable of tuning to any of the 25 khz channels from 112 MHz to 137 MHz. (2) A VDL Mode 4 stations shall: (a) be capable of receiving two channels simultaneously; and (b) use two assigned frequencies as Global Signalling Channels, to support user communications and link management functions. 57.-(1) The VDL Mode 4 system shall- (a) support ATN/IPS-compliant sub network services; (b) provide code-independent and byte-independent transfer of data. (c) provide link layer broadcast services. 40

41 (d) provide link layer point-to-point services. (e) provide air-air communications, without ground support, as well as air-ground communications (f) establish and maintain a reliable communications path between the aircraft and the ground system while allowing, but not requiring, manual intervention when supporting air-ground operations. (g) provide the capability for deriving time from timeof-arrival measurements of received VDL Mode 4 transmissions whenever externally derived estimates of time are unavailable. (2) A mobile VDL Mode 4 DLS station shall transition from one ground VDL Mode 4 DLS station to another as required. (3) Mobile and ground VDL Mode 4 stations shall access the physical medium operating in simplex mode. Coordination of channel utilization 58. Transmissions shall be scheduled relative to UTC, to ensure efficient use of shared channels and to avoid unintentional slot re-use on a regional basis. PART VIII AERONAUTICAL FIXED TELECOMMUNICATION NETWORK Characteristics of Interregional Aeronautical Fixed Service circuits Technical provisions relating to international ground-ground data interchange at medium and higher signalling rates. Aircraft Addressing 59. Interregional Aeronautical Fixed Service circuits being implemented or upgraded shall employ high quality telecommunications service and the modulation rate shall take into account traffic volumes expected under both normal and alternate route conditions. 60. The technical provisions related to international ground-ground data interchange at medium and higher signalling rates for AFTN networks shall be as specified in the Eleventh Schedule. 61.-(1) The aircraft address shall be one of twenty-four-bit aircraft addresses allocated by ICAO to the 41

42 System State of Registry or common mark registering authority and assigned as specified in the Twelfth Schedule. (2) Non-aircraft transponders that are installed on aerodrome surface vehicles, obstacles or fixed Mode S target detection devices for surveillance or radar monitoring purposes shall be assigned 24-bit aircraft addresses. (3) Mode S transponders used in accordance with sub regulation (2) shall not have any negative impact on the performance of existing ATS surveillance systems and ACAS. PART IX POINT-TO-MULTIPOINT COMMUNICATIONS Service via satellite for the dissemination of Aeronautical Information Service via satellite for the dissemination of World Area Forecast System products 62. Point-to-multipoint telecommunication service via satellite to support the dissemination of Aeronautical Information shall be based on full-time, non-pre-emptible, protected services as defined in the relevant Telecommunication Standardization Sector of the International Telecommunications Union Recommendations. 63. System characteristics shall include the following: (a) frequency-c-band, earth-to-satellite, 6 GHz band, satellite-to-earth, 4 GHz band; (b) capacity with effective signalling rate of not less than bits/s; (c) bit error rates-better than 1 in 10 7 ; (d) forward error correction; and (e) availability per cent. PART X HIGH FREQUENCY DATA LINK SYSTEM System architecture Aircraft and Ground Station Subsystems 64. The High Frequency Data Link system shall- (a) consist of one or more ground and aircraft station subsystems, which implement the High Frequency Data Link protocol specified in regulation 77. (b) include a ground management subsystem regulations The HFDL aircraft station subsystem and the HFDL ground station subsystem shall include the following functions: 42

43 (a) HF transmission and reception; (b) data modulation and demodulation; and (c) HFDL protocol implementation and frequency selection. Operational coverage Requirements for carriage of HFDL equipment Ground station networking Ground station synchronization Quality of service HF Data Link Protocol Ground Management Subsystem 66. Frequency assignments for HFDL shall be protected throughout their Designated Operational Coverage area. 67.-(1) Requirements for mandatory carriage of HFDL equipment shall be made on the basis of regional air navigation agreements that specify the airspace of operation and the implementation timescale. (2) The agreement in sub regulation (1) shall provide advance notice of at least two years for the mandatory carriage of airborne systems. 68. HFDL ground station subsystems shall interconnect through a common ground management subsystem 69.-(1) Synchronization of HFDL ground station subsystems shall be to within ±25 ms of UTC. (2) For any station not operating within ±25 ms of UTC, appropriate notification shall be made to all aircraft and ground station subsystems to allow for continued system operation. 70.-(1) The undetected error rate for a network user packet which contains between 1 and 128 octets of user data shall be equal to or less than 1 in (2) Transit and transfer delays for network user packets of 128 octets shall not exceed the values of the specifications in Table 11-1 in the Eighteenth Schedule to these Regualtions. 71. The HFDL protocol shall consist of a physical layer, a link layer, and a sub-network layer, as specified in the Thirteenth Schedule to these Regualtions. 72. The ground management subsystem shall: (a) perform the functions necessary to establish and maintain communications channels between the HFDL ground and aircraft station subsystems; 43

44 (b) interface with the ground station subsystem in order to exchange control information required for frequency management, system table management, log status management, channel management, and Quality of Service data collection. PART XI UNIVERSAL ACCESS TRANSCEIVER (UAT) Universal Access Transceiversystem characteristics of aircraft and ground stations Mandatory carriage requirements 73. The Universal Access Transmitter physical layer and system characteristics of aircraft and ground stations shall be as specified in the Fourteenth Schedule to these Regulations. 74. Requirements for mandatory carriage of UAT equipment shall be made on the basis of regional air navigation agreements which specify the airspace of operation and the implementation timescales for the carriage of equipment, including the appropriate lead time. PART XII AERONAUTICAL MOBILE SERVICE Air-Ground VHF Communication System characteristics Single side band(ssb) HF Communication System Characteristics 75.-(1) The characteristics of the air-ground VHF communication system used in the International Aeronautical Mobile Service shall be in conformity with the specifications contained in the Fifteenth Schedule to these Regulations. (2) The systems characteristics for both ground and airborne installation shall conform to the specifications of the Fifteenth Schedule to these Regulations. 76. The characteristics of the air-ground HF Single Side Band system, where used in the Aeronautical Mobile Service, shall be in conformity with the specifications of the Fifteenth Schedule to these Regulations. Selcal System 77.-(1) Where a SELCAL system is installed, the 44

45 system characteristics in the Sixteenth Schedule to these Regulations shall be applied. (2) Aeronautical Stations which are required to communicate with SELCAL-equipped aircraft shall have SELCAL encoders in accordance with the red group specified in the table of tone frequencies set out in the Sixteenth Schedule to these Regulations, as from 1 September (3) SELCAL codes using the tones Red P, Red Q, Red R, and Red S shall be assigned after 1 September 1985, PART XIII AERONAUTICAL SPEECH CIRCUITS Technical provisions relating to International Aeronautical speech circuit switching and signalling for ground-ground applications 78.-(1) The use of circuit switching and signalling to provide speech circuits to interconnect ATS units not interconnected by dedicated circuits shall be by agreement between the Administrations concerned. (2) The application of aeronautical speech circuit switching and signalling shall be made on the basis of regional air navigation agreements. (3) The Air Traffic Control communication requirements defined in the Civil Aviation (Air Traffic Services ) Regulations shall be met by implementation of one or more of the following basic three call types- (a) instantaneous access; (b) direct access; and (c) indirect access (4) Subject to sub regulation (3), the following functions shall be provided in order to meet the requirements specified in Civil Aviation (Air Traffic Services ) Regulations 2016 (a) means of indicating the calling or called party identity; (b) means of initiating urgent or priority calls; and (c) conference capabilities. (5) The characteristics of the circuits used in aeronautical speech circuit switching and signalling shall conform to appropriate ISOor IEC international standards and Telecommunication Standardization Sector of the International Telecommunications Union recommendations. (6) Digital signalling systems shall be used wherever 45

46 their use can be justified in terms of any of the following: (a) improved quality of service; (b) improved user facilities; or (c) reduced costs where quality of service is maintained (7) The characteristics of supervisory tones to be used such as ringing, busy, number unobtainable shall conform to appropriate Telecommunication Standardization Sector of the International Telecommunications Union, recommendations. (8) The international aeronautical telephone network numbering scheme shall be used in order to take advantage of the benefits of interconnecting regional and national aeronautical speech networks. PART XIV EMERGENCY LOCATOR TRANSMITTER FOR SEARCH AND RESCUE Operating frequencies Emergency Locator transmitters Register 79.-(1) All installations of emergency locator transmitters operating on 406 MHz shall meet the provisions specified in regulation 88. (2) All installations of emergency locator transmitters operating on MHz shall meet the provisions specified in regulation 87. (3) Emergency locator transmitters shall operate on 406 MHz and MHz simultaneously. (4) All emergency locator transmitters installed on or after 1 January 2002 shall operate simultaneously on 406 MHz and MHz. (5) The technical characteristics for the 406 MHz component of an integrated ELT shall be in accordance with regulation 88. (6) The technical characteristics for the MHz component of an integrated ELT shall be in accordance with regulation (1) The Authority shall make arrangements to have a 406 MHz Emergency Locator transmitters register and shall ensure that the register is updated whenever necessary. (2) Register information regarding the Emergency Locator transmitters shall be immediately available to search and rescue authorities. 46

47 (3) Emergency Locator transmitters register information shall include the following: (a) transmitter identification expressed in the form of an alphanumerical code of 15 hexadecimal characters; (b) transmitter manufacturer, model and serial number; (c) COSPAS-SARSAT (type approval number; (d) name, address and emergency telephone number of the owner and operator; (e) name, address and telephone number of other emergency contacts to whom the owner or the operator is known; (f) aircraft manufacturer and type; and (g) colour of the aircraft. Specification for the MHz component of Emergency Locator Transmitter 81.-(1) Emergency Locator Transmitters shall operate on MHz and the frequency tolerance shall not exceed plus or minus per cent. (2) The emission from an Emergency Locator transmitters under normal conditions and attitudes of the antenna shall be vertically polarized and essentially omnidirectional in the horizontal plane. (3) Over a period of 48 hours of continuous operation, at an operating temperature of minus 20 C, the Peak Effective Radiated Power shall at no time be less than 50 mw. (4) The type of emission shall be A3X and any other type of modulation that meets the requirements of sub regulations (5), (6) and (7) shall be used provided that the emission does not prejudice precise location of the beacon by homing equipment. (5) The carrier shall be amplitude modulated at a modulation factor of at least (6) The modulation applied to the carrier shall have a minimum duty cycle of 33 per cent. (7) The emission shall have a distinctive audio characteristic achieved by amplitude modulating the carrier with an audio frequency sweeping downward over a range of not less than 700 Hz within the range Hz to 300 Hz and with a sweep repetition rate of between 2 Hz and 4 Hz. (8) The emission shall include a clearly defined carrier frequency distinct from the modulation sideband components; 47

48 in particular, at least 30 per cent of the power shall be contained at all times within plus or minus 30 Hz of the carrier frequency on MHz. Specification for the 406 MHz component of Emergency Locator Transmitter Transmitter identification coding 82.-(1) Emergency Locator Transmitters shall operate on one of the frequency channels assigned for use in the frequency band to MHz. (2) The period between transmissions shall be 50 seconds plus or minus 5 per cent. (3) Over a period of 24 hours of continuous operation at an operating temperature of 20 C, the transmitter power output shall be within the limits of 5 W plus or minus 2 db. (4) The 406 MHz Emergency Locator Transmitters shall be capable of transmitting a digital message. 83.-(1) Emergency locator transmitters operating on 406 MHz shall be assigned a unique coding for identification of the transmitter or aircraft on which it is carried. (2) The emergency locator transmitter shall be coded in accordance with either the aviation user protocol or one of the serialized user protocols specified in the Seventeenth Schedule and shall be registered with the appropriate the Authority. 48

49 PART XV EXEMPTIONS Requireme nts for application for exemption. 84.-(1) A person may apply to the Authority for an exemption from any provision of these Regulations. (2) Unless in case of emergency, a person requiring exemptions from any of these Regulations shall make an application to the Authority at least sixty days prior to the proposed effective date, giving the following information- (a) name and contact address including electronic mail and fax if any; (b) telephone number; (c) a citation of the specific requirement from which the applicant seeks exemption; (d) justification for the exemption; (e) a description of the type of operations to be conducted under the proposed exemption; (f) the proposed duration of the exemption; (g) an explanation of how the exemption would be in the public interest; (h) a detailed description of the alternative means by which the applicant will ensure a level of safety equivalent to that established by the regulation in question; (i) A safety risk assessment carried out in respect of the exemption applied for; (j) if the applicant handles international operations and seeks to operate under the proposed exemption, an indication whether the exemption would contravene any provision of the Standards and Recommended Practices of the International Civil Aviation Organization (ICAO); and (k) any other information that the Authority may require. (3) Where the applicant seeks emergency processing of an application for exemption, the application shall contain supporting facts and reasons for not filing the application within the time specified in sub regulation (2) and satisfactory reason for deeming the application an emergency. (4) The Authority may in writing, refuse an application made under sub regulation (3), where in the opinion of the Authority, the reasons given for emergency processing are not satisfactory. 49

50 (6) The application for exemption shall be accompanied by fee prescribed by the Authority. Review and publication Evaluation of the request. 85.-(1) The Authority shall review the application for exemption made under regulation 52 for accuracy and compliance and if the application is satisfactory, the Authority shall publish a detailed summary of the application for comments, within a prescribed time, in either- (a) aeronautical information circular; or (b) a daily newspaper with national circulation. (2) Where application requirements have not been fully complied with, the Authority shall request the applicant in writing, to comply with the requirements, prior to publication or making a decision under sub regulation (3). (3) If the request is for emergency relief, the Authority shall publish the decision as soon as possible after processing the application. 86.-(1) Where the application requirements have been satisfied, the Authority shall conduct an evaluation of the request to include- (a) determination of whether an exemption would be in the public interest; (b) a determination, after a technical evaluation of whether the applicant s proposal would provide a level of safety equivalent to that established by the regulation, although where the Authority decides that a technical evaluation of the request would impose a significant burden on the Authority s technical resources, the Authority may deny the exemption on that basis; (c) a determination of whether a grant of the exemption would contravene these Regulations; and (d) a recommendation based on the preceding elements, of whether the request should be granted or denied, and of any conditions or limitations that should be part of the exemption. (2) The Authority shall notify the applicant in writing of, the decision to grant or deny the request and publish a detailed summary of its evaluation and decision. 50

51 (3) The summary referred to in sub-regulation (2) shall specify the duration of the exemption and any conditions or limitations of the exemption. (4) If the exemption affects a significant population of the aviation community of the United Republic of Tanzania the Authority shall publish the summary in aeronautical information circular. PART XVI GENERAL PROVISIONS Drug and alcohol testing and reporting. 87.-(1) Any person who performs any function prescribed by these Regulations directly or by contract under the provisions of these Regulations may be tested for drug or alcohol usage. (2) A person who- (a) refuses to submit to a test to indicate the percentage by weight of alcohol in the blood; or (b) refuses to submit to a test to indicate the presence of narcotic drugs, marijuana, or depressant or stimulant drugs or substances in the body, when requested by a law enforcement officer or the Authority, or refuses to furnish or to authorise the release of the test results requested by the Authority shall- (i) be denied any licence, certificate, rating, qualification, or authorisation issued under these Regulations for a period of up to one year from the date of that refusal; or (ii) have their licence, certificate, rating, qualification, or authorisation issued under these Regulations suspended or revoked. (3) Any person who is convicted for the violation of any local or national statute relating to the use growing, processing, manufacture, sale, disposition, possession, transportation, or importation of narcotic drugs, marijuana, or depressant or stimulant drugs or substances, shall- (a) be denied any license, certificate, rating, qualification, or authorisation issued under these Regulations for a period of up to one year after the date of conviction; or (b) have their licence, certificate, rating, qualification, or authorisation issued under these Regulations suspended or revoked. 51

52 Change of Name Change of address Replaceme nt of documents. Use and retention of documents and records. 89.-(1) A CNSP holder of a certificate issued under these Regulations may apply to the Authority for- (a) replacement of the certificate if lost or destroyed; (b) change of name on the certificate; or (c) an endorsement on the certificate. (2) When applying under paragraph (1), the holder of a certificate shall submit to the Authority- (a) the original certificate or a copy thereof in case of loss; and (b) a court order, or other legal document verifying the name change. (3) The Authority shall return to the holder of a certificate, with the appropriate changes applied for, if any, the originals specified under paragraph (2) and, where necessary, retain copies thereof. 90.-(1) A holder of a certificate issued shall notify the Authority of the change in the physical and mailing address within fourteen days of such change. (2) A person who does not notify the Authority of the change in the physical and mailing address within the time frame specified in sub-regulation (1) shall not exercise the privileges of the certificate. 91. A person may apply to the Authority in the prescribed form for replacement of documents issued under these Regulations if such documents are lost or destroyed. 92.-(1) A person shall not- (a) use any certificate or exemption issued or required by or under these Regulations which has been forged, altered, cancelled, or suspended, or to which he is not entitled; or (b) forge or alter any certificate or exemption issued or required by or under these Regulations; or (c) lend any certificate or exemption issued or required by or under these Regulations to any other person; or (d) make any false representation for the purpose of procuring for himself or any other person the grant, issue, renewal or variation of any such certificate or 52

53 exemption. (e) mutilate, alter, render illegible or destroy any records, or any entry made therein, required by or under these Regulations to be maintained, or knowingly make, or procure or assist in the making of, any false entry in any such record, or wilfully omit to make a material entry in such record. (2) All records required to be maintained by or under these Regulations shall be recorded in a permanent and indelible material. (3) A person shall not issue any certificate- (a) or exemption under these Regulations unless he is authorised to do so by the Authority; (b) referred to in sub-regulation (3) unless he has satisfied himself that all statements in the certificate are correct, and that the applicant is qualified to hold that certificate. Reports of violation Failure to comply with direction Aeronautic al fees 93.-(1) Any person who knows of a violation of the Act, or any Regulations, rules, or orders issued there under, shall report it to the Authority. (2) The Authority may determine the nature and type of investigation or enforcement action that need to be taken. 94. Any person who fails to comply with any direction given to him by the Authority or by any authorised person under any provision of these Regulations commits an offence. 95.-(1) The Authority shall notify in writing the fees to be charged in connection with the issue, renewal or variation of any certificate, test, inspection or investigation required by, or for the purpose of these Regulations any orders, notices or proclamations made there under. (2) An applicant for anything under these Regulations shall, before the application is accepted, be required to pay the fee so chargeable for the respective application. (3) Where a payment has been made in terms of sub regulation (2) and the applicant decides to withdraw the application, the Authority shall not refund the payment made. 53

54 PART XVII OFFENCES AND PENALTIES Penalties General penalty 96.-(1) A person who contravenes any provision of these Regulations, orders, notices or proclamations made there under shall, upon conviction, be liable to a fine not exceeding one million shillings or to imprisonment for a term not more than six months or both, and in the case of a continuing contravention, each day of the contravention shall constitute a separate offence. (2) If it is proved that an act or omission of any person, which would otherwise have been a contravention by that person of a provision of these Regulations, orders, notices or proclamations made there under was due to any cause not avoidable by the exercise of reasonable care by that person, the act or omission shall be deemed not to be a contravention by that person of that provision. (3) Where any person is aggrieved by any order made under these Regulations the person may, within twenty one days of such order being made, appeal against the order to a court of law with competent jurisdiction. 97. A person who contravenes any provision of these Regulations for which no penalty has been provided, commits an offence and- (a) shall, on conviction be liable to a fine of the sum equivalent in Tanzanian shillings of five hundred United States dollars; and (b) may, on conviction have his certificate, approval, authorisation, exemption or such other document revoked or suspended. 54

55 FIRST SCHEDULE (Made under regulation 21) 1.1 Tables for Aeronautical Telecommunications Network (ATN) Mapping- 1.2 Table 1: Mapping of ATN communication priorities Note.-The network layer priorities shown in the table apply only to connectionless network priority and do not apply to sub-network priority. 55

56 1.3 Table 2. Mapping of ATN network priority to mobile sub-network priority 56

57 SECOND SCHEDULE (Made under regulation 45(a)) SSR MODE S AIR GROUND DATA LINK 1. MODE S CHARACTERISTICS 1.1 General provisions Note 1. Reference ISO document. When the term ISO 8208 is referred to in this standard, it means the ISO Standard Information technology Data communications X.25 Packet Layer Protocol for Data Terminal Equipment, Reference Number ISO/IEC 8208: 1990(E). Note 2. The overall architecture of the Mode S sub-network is presented in the diagram on the following page. Note 3. The processing splits into three different paths. The first consists of the processing of switched virtual circuits (SVCs), the second consists of the processing of Mode S specific services, and the third consists of the processing of sub-network management information. SVCs utilize the reformatting process and the ADCE or GDCE function. Mode S specific services utilize the Mode S specific services entity (SSE) function Message categories. The Mode S subnetwork shall only carry aeronautical communications classified under categories of flight safety and flight regularity as specified in Civil Aviation ( Communication Procedures) Regulations Signals in space. The signal-in-space characteristics of the Mode S subnetwork shall conform to the provisions contained in Civil Aviation ( Surveillance and Collision Avoidance systems) Regulations Code and byte independency. The Mode S subnetwork shall be capable of code and byte independent transmission of digital data Data transfer. Data shall be conveyed over the Mode S data link in segments using either standard length message (SLM) protocols or extended length message (ELM) protocols. Note 1. An SLM segment is the contents of one 56-bit MA or MB field. An ELM segment is the contents of one 80-bit MC or MD field. Note 2. An SLM frame is the contents of up to four linked MA or MB fields. An ELM frame is the contents of 2 to 16 MC or 1 to 16 MD fields Bit numbering. In the description of the data exchange fields, the bits shall be numbered in the order of their transmission, beginning with bit 1. Bit numbers shall continue through the second and higher segments of multi-segment frames. Unless otherwise 57

58 Stated, numerical values encoded by groups (fields) of bits shall be encoded using positive binary notation and the first bit transmitted shall be the most significant bit (MSB) Unassigned bits. When the length of the data is not sufficient to occupy all bit positions within a message field or subfield, the unassigned bit positions shall be set to Frames UPLINK FRAMES SLM frame. An uplink SLM frame shall be composed of up to four selectively addressed Comm-A segments. 58

59 Functional elements of the Mode S subnetwork Note. Each Comm-A segment (MA field) received by the ADLP is accompanied by the first 32 bits of the interrogation that delivered the segment ( of Annex 10, Volume IV). Within these 32 bits is the 16-bit special designator (SD) field ( of Annex 10, Volume IV) SD field. When the designator identification (DI) field (bits 14-16) has a code value of 1 or 7, the special designator (SD) field (bits 17-59

60 32) of each Comm-A interrogation shall be used to obtain the interrogator identifier subfield (IIS, bits 17-20) and the linked Comm-A subfield (LAS, bits 30-32). The action to be taken shall depend on the value of LAS. The contents of LAS and IIS shall be retained and shall be associated with the Comm-A message segment for use in assembling the frame as indicated below. All fields other than the LAS field shall be as defined in the Civil Aviation (Surveillance and Collision Avoidance Systems) Regulations. Note: The SD field structure is shown in Figure in the Second Schedule LAS coding. The 3-bit LAS subfield shall be coded as follows: LAS MEANING 0 single segment 1 linked, 1st segment 2 linked, 2nd but not final segment 3 linked, 3rd but not final segment 4 linked, 4th and final segment 5 linked, 2nd and final segment 6 linked, 3rd and final segment 7 unassigned Single segment SLM frame. If LAS = 0, the data in the MA field shall be considered a complete frame and shall be made available for further processing Multiple segment SLM frame. The ADLP shall accept and assemble linked 56-bit Comm-A segments associated with all sixteen possible interrogator identifier (II) codes. Correct linking of Comm-A segments shall be achieved by requiring that all Comm-A segments have the same value of IIS. If LAS = 1 through 6, the frame shall consist of two to four Comm-A segments as specified in the following paragraphs Initial segment. If LAS = 1, the MA field shall be assembled as the initial segment of an SLM frame. The initial segment shall be stored until all segments of the frame have been received or the frame is cancelled. 60

61 Intermediate segment. If LAS = 2 or 3, the MA field shall be assembled in numerical order as an intermediate segment of the SLM frame. It shall be associated with previous segments containing the same value of IIS Final segment. If LAS = 4, 5 or 6, the MA field shall be assembled as the final segment of the SLM frame. It shall be associated with previous segments containing the same value of IIS Frame completion. The frame shall be considered complete and shall be made available for further processing as soon as all segments of the frame have been received Frame cancellation. An incomplete SLM frame shall be cancelled if one or more of the following conditions apply: a) a new initial segment (LAS = 1) is received with the same value of IIS. In this case, the new initial segment shall be retained as the initial segment of a new SLM frame; b) the sequence of received LAS codes (after the elimination of duplicates) is not contained in the following list: 1) LAS = 0 2) LAS = 1,5 3) LAS = 1,2,6 4) LAS = 1,6,2 5) LAS = 1,2,3,4 6) LAS = 1,3,2,4 7 LAS = 1,2,4,3 8) LAS = 1,3,4,2 9) LAS = 1,4,2,3 10) LAS = 1,4,3,2 c) Tc seconds have elapsed since the last Comm-A segment with the same value of IIS was received (Table 5-1) Segment cancellation. A received segment for an SLM frame shall be discarded if it is an intermediate or final segment and no initial segment has been received with the same value of IIS. 61

62 Segment duplication. If a received segment duplicates a currently received segment number with the same value of IIS, the new segment shall replace the currently received segment. Note. The action of the Mode S subnetwork protocols may result in the duplicate delivery of Comm-A segments ELM frame. An uplink ELM frame shall consist of from 20 to 160 bytes and shall be transferred from the interrogator to the transponder using the protocol defined in the Civil Aviation (Surveillance and Collision Avoidance Systems) Regulations. The first 4 bits of each uplink ELM segment (MC field) shall contain the interrogator identifier (II) code of the Mode S interrogator transmitting the ELM. The ADLP shall check the II code of each segment of a completed uplink ELM. If all of the segments contain the same II code, the II code in each segment shall be deleted and the remaining message bits retained as user data for further processing. If all of the segments do not contain the same II code, the entire uplink ELM shall be discarded. Note. An uplink ELM frame consists of two to sixteen associated Comm-C segments, each of which contains the 4-bit II code. Therefore, the capacity for packet transfer is 19 to 152 bytes per uplink ELM frame DOWNLINK FRAMES SLM frame. A downlink SLM frame shall be composed of up to 4 Comm-B segments. The MB field of the first Comm-B segment of the frame shall contain a 2-bit linked Comm-B subfield (LBS, bits 1 and 2 of the MB field). This subfield shall be used to control linking of up to four Comm-B segments. Note. The LBS uses the first 2-bit positions in the first segment of a multi or single segment downlink SLM frame. Hence, 54 bits are available for Mode S packet data in the first segment of a downlink SLM frame. The remaining segments of the downlink SLM frame, if any, have 56 bits available LBS coding. Linking shall be indicated by the coding of the LBS subfield of the MB field of the initial Comm-B segment of the SLM frame. The coding of LBS shall be as follows: 62

63 LBS MEANING 0 single segment 1 initial segment of a two-segment SLM frame 2 initial segment of a three-segment SLM frame 3 initial segment of a four-segment SLM frame Linking protocol In the Comm-B protocol, the initial segment shall be transmitted using the air-initiated or multisitedirected protocols. The LBS field of the initial segment shall indicate to the ground the number of additional segments to be transferred (if any). Before the transmission of the initial segment to the transponder, the remaining segments of the SLM frame (if any) shall be transferred to the transponder for transmission to the interrogator using the groundinitiated Comm-B protocol. These segments shall be accompanied by control codes that cause the segments to be inserted in groundinitiated Comm-B registers 2, 3 or 4, associated respectively with the second, third, or fourth segment of the frame Close-out of the air-initiated segment that initiated the protocol shall not be performed until all segments have been successfully transferred. Note. The linking procedure including the use of the ground-initiated Comm-B protocol is performed by the ADLP Directing SLM frames. If the SLM frame is to be multisite-directed, the ADLP shall determine the II code of the Mode S interrogator or cluster of interrogators that shall receive the SLM frame ELM FRAME Note. A downlink ELM consists of one to sixteen associated Comm-D segments Procedure. Downlink ELM frames shall be used to deliver messages greater than or equal to 28 bytes and shall be formed using the protocol defined in the Civil Aviation (Surveillance and Collision Avoidance Systems) Regulations 63

64 Directing ELM frames. If the ELM frame is to be multisite-directed, the ADLP shall determine the II code of the Mode S interrogator or cluster of interrogators that shall receive the ELM frame XDLP frame processing. Frame processing shall be performed on all Mode S packets (except for the MSP packet). Frame processing for Mode S specific services shall be performed as specified in Packet length. All packets (including a group of packets multiplexed into a single frame) shall be transferred in a frame consisting of the smallest number of segments needed to accommodate the packet. The user data field shall be an integral multiple of bytes in length. A 4-bit parameter (LV) shall be provided in the Mode S DATA, CALL REQUEST, CALL ACCEPT, CLEAR REQUEST and INTERRUPT packet headers so that during unpacking no additional bytes are added to the user data field. The LV field shall define the number of full bytes used in the last segment of a frame. During LV calculations, the 4-bit II code in the last segment of an uplink ELM message shall be (1) ignored for uplink ELM frames with an odd number of Comm-C segments and (2) counted for uplink ELM frames with an even number of Comm-C segments. The value contained in the LV field shall be ignored if the packet is multiplexed Multiplexing. When multiplexing multiple Mode S packets into single SLM on ELM frame, the following procedures shall be used. Multiplexing of the packets within the ADLP shall not be applied to packets associated with SVCs of different priorities. Note. Multiplexing is not performed on MSP packets Multiplexing optimization When multiple packets are awaiting transfer to the same XDLP, they shall be multiplexed into a single frame in order to optimize throughput, provided that packets associated with SVCs of different priorities are not multiplexed together Structure. The structure of the multiplexed packets shall be as follows: 64

65 Note. A number in the field signifies the field length in bits; v signifies that the field is of variable length Multiplexing header. The header for the multiplexed packets shall be as follows: Where, Data packet type (DP) = 0 MSP packet type (MP) = 1 Supervisory packet (SP) = 3 Supervisory type (ST) = Length. This field shall contain the length of the following packet in bytes. Any error detected in a multiplexed DATA packet, such as inconsistency between length as indicated in the LENGTH field and the length of the frame hosting that packet, shall result in the discarding of the packet unless the error can be determined to be limited to the LENGTH field, in which case a REJECT packet with the expected PS value can be sent For multiplex packets, if the entire packet cannot be demultiplexed, then the first constituent packet shall be treated as a format error, and the remainder should be discarded Termination. The end of a frame containing a sequence of multiplexed packets shall be determined by one of the following events: a) a length field of all zeros; or b) less than eight bits left in the frame MODE S CHANNEL SEQUENCE PRESERVATION Application. In the event that multiple Mode S frames from the same SVC are awaiting transfer to the same XDLP, the following procedure shall be used. 65

66 Procedure SLM frames. SLM frames awaiting transfer shall be transmitted in the order received ELM frames. ELM frames awaiting transfer shall be transmitted in the order received GDLP FRAME PROCESSING GENERAL PROVISIONS The GDLP shall determine the data link capability of the ADLP/transponder installation from the data link capability report before performing any data link activity with that ADLP GDLP frame processing shall provide to the interrogator all data for the uplink transmission that are not provided directly by the interrogator Delivery status. GDLP frame processing shall accept an indication from the interrogator function that a specified uplink frame that was previously transferred to the interrogator has been successfully delivered over the ground-to air link Aircraft address. GDLP frame processing shall receive from the interrogator along with the data in each downlink SLM or ELM frame, the 24-bit address of the aircraft that transmitted the frame. GDLP frame processing shall be capable of transferring to the interrogator the 24-bit address of the aircraft that is to receive an uplink SLM or ELM frame Mode S protocol type identification. GDLP frame processing shall indicate to the interrogator the protocol to be used to transfer the frame: standard length message protocol, extended length message protocol or broadcast protocol Frame determination. A Mode S packet (including multiplexed packets but excluding MSP packets) intended for uplink and less than or equal to 28 bytes shall be sent as an SLM frame. A Mode S packet greater than 28 bytes shall be sent as an uplink ELM frame for transponders 66

67 with ELM capability, using M-bit processing as necessary). If the transponder does not have ELM capability, packets greater than 28 bytes shall be sent using the M-bit or S-bit assembly procedures as necessary and multiple SLM frames. Note. The Mode S DATA, CALL REQUEST, CALL ACCEPT, CLEAR REQUEST and INTERRUPT packets are the only Mode S packets that use M-bit or S-bit sequencing ADLP FRAME PROCESSING General provisions. With the possible exception of the last 24 bits (address/parity), ADLP frame processing shall accept from the transponder the entire content of both 56-bit and 112-bit received uplink transmissions, excluding all call and ACAS interrogations. ADLP frame processing shall provide to the transponder all data for the downlink transmission that is not provided directly by the transponder Delivery status. ADLP frame processing shall accept an indication from the transponder that a specified downlink frame that was previously transferred to the transponder has been closed out Interrogator identifier. ADLP frame processing shall accept from the transponder, along with the data in each uplink SLM and ELM, the interrogator identifier (II) code of the interrogator that transmitted the frame. ADLP frame processing shall transfer to the transponder the II code of the interrogator or cluster of interrogators that shall receive a multisite-directed frame Mode S protocol type identification. ADLP frame processing shall indicate to the transponder the protocol to be used to transfer the frame: ground-initiated, air-initiated, broadcast, multisite-directed, standard length or extended length Frame cancellation. ADLP frame processing shall be capable of cancelling downlink frames previously transferred to the transponder for transmission but for which a close-out has not been indicated. If more than one frame is stored within the transponder, the cancellation procedure shall be capable of cancelling the stored frames selectively. 67

68 Frame determination. A Mode S packet (including multiplexed packets but excluding MSP packets) intended for downlink and less than or equal to 222 bits shall be sent as an SLM frame. A Mode S packet greater than 222 bits shall be sent as a downlink ELM frame for transponders with ELM capability using M-bit processing as necessary. When M-bit processing is used, all ELM frames containing M = 1 shall contain the maximum number of ELM segments that the transponder is capable of transmitting in response to one requesting interrogation (UF = 24). If the transponder does not have ELM capability, packets greater than 222 bits shall be sent using the M-bit or S-bit assembly procedures and multiple SLM frames PRIORITY MANAGEMENT ADLP priority management. Frames shall be transferred from the ADLP to the transponder in the following order of priority (highest first): a) Mode S specific services; b) search requests ; c) frames containing only high priority SVC packets; and d) frames containing only low priority SVC packets GDLP PRIORITY MANAGEMENT Uplink frames shall be transferred in the following order of priority (highest first): a) Mode S specific services; b) frames containing at least one Mode S ROUTE packet;; c) frames containing at least one high priority SVC packet; and d) frames containing only low priority SVC packets. 1.3 Data exchange interfaces THE DTE ISO 8208 INTERFACE General provisions. The interface between the XDLP and the DTE(s) shall conform to ISO 8208 packet layer protocol (PLP). The XDLP shall support the procedures of the DTE as specified in ISO As such, the XDLP shall contain a DCE (5.2.4). 68

69 Physical and link layer requirements for the DTE/DCE interface. The requirements are: (a) the interface shall be code and byte independent and shall not impose restrictions on the sequence, order, or pattern of the bits transferred within a packet; and (b) the interface shall support the transfer of variable length network layer packets DTE ADDRESS Ground DTE address. The ground DTE address shall have a total length of 3 binary coded decimal (BCD) digits, as follows: X0X1X2 X0 shall be the most significant digit. Ground DTE addresses shall be decimal numbers in the range of 0 through 255 coded in BCD. Assignment of the DTE address shall be a local issue. All DTEs connected to GDLPs having overlapping coverage shall have unique addresses. GDLPs which have a flying time less than (Table 5-1) between their coverage areas shall be regarded as having overlapping coverage Mobile DTE address. The mobile DTE address shall have a total length of 10 BCD digits, as follows: X0X1X2X3X4X5X6X7X8X9 X0 shall be the most significant digit. The digits X0 to X7 shall contain the octal representation of the aircraft address coded in BCD. The digits X8X9 shall identify a sub-address for specific DTEs on board an aircraft. This sub-address shall be a decimal number in the range of 0 and 15 coded in BCD. The following sub-address assignments shall be used: 00 ATN router 01 to 15 Unassigned Illegal DTE addresses. DTE addresses outside of the defined ranges or not conforming to the formats for the ground and mobile DTE 69

70 addresses and shall be defined to be illegal DTE addresses. The detection of an illegal DTE address in a CALL REQUEST packet shall lead to a rejection of the call PACKET LAYER PROTOCOL REQUIREMENTS OF THE DTE/DCE INTERFACE Capabilities. The interface between the DTE and the DCE shall conform to ISO 8208 with the following capabilities: (a) expedited data delivery, i.e. the use of INTERRUPT packets with a user data field of up to 32 bytes; (b) priority facility (with two levels, (c) fast select and (d) Called/calling address extension facility, if required by local conditions (i.e. the XDLP is connected to the DTE via a network protocol that is unable to contain the Mode S address as defined). Other ISO 8208 facilities and the D-bit and the Q-bit shall not be invoked for transfer over the Mode S packet layer protocol Parameter values. The timer and counter parameters for the DTE/DCE interface shall conform to the default ISO 8208 values MODE S SPECIFIC SERVICES INTERFACE ADLP Note. Mode S specific services consist of the broadcast Comm-A and Comm-B, GICB and MSP General provisions. The ADLP shall support the accessing of Mode S specific services through the provision of one or more separate ADLP interfaces for this purpose Functional capability. Message and control coding via this interface shall support all of the capabilities specified in GDLP General provisions. The GDLP shall support the accessing of Mode S specific services through the provision of a separate GDLP 70

71 interface for this purpose and/or by providing access to these services through the DTE/DCE interface Functional capability. Message and control coding via this interface shall support all of the capabilities specified in ADLP/TRANSPONDER INTERFACE TRANSPONDER TO ADLP The ADLP shall accept an indication of protocol type from the transponder in connection with data transferred from the transponder to the ADLP. This shall include the following types of protocols: (a) surveillance interrogation; (b) Comm-A interrogation; (c) Comm-A broadcast interrogation; and (d) uplink ELM. The ADLP shall also accept the II code of the interrogator used to transmit the surveillance, Comm-A or uplink ELM. Note. Transponders will not output all-call and ACAS information on this interface The ADLP shall accept control information from the transponder indicating the status of downlink transfers. This shall include: (a) Comm-B close-out; (b) Comm-B broadcast timeout; and (c) downlink ELM close-out The ADLP shall have access to current information defining the communication capability of the Mode S transponder with which it is operating. This information shall be used to generate the data link capability report (1.9) ADLP TO TRANSPONDER The ADLP shall provide an indication of protocol type to the transponder in connection with data transferred from the ADLP to the transponder. This shall include the following types of protocols: (a) ground-initiated Comm-B; 71

72 (b) air-initiated Comm-B; (c) multisite-directed Comm-B; (d) Comm-B broadcast; (e) downlink ELM; and (f) multisite-directed downlink ELM. The ADLP shall also provide the II code for transfer of a multisitedirected Comm-B or downlink ELM and the Comm-B data selector (BDS) code ( of Manual of ANS standards Part II, Volume IV) for a ground-initiated Comm-B The ADLP shall be able to perform frame cancellation GDLP/MODE S INTERROGATOR INTERFACE INTERROGATOR TO GDLP The GDLP shall accept an indication of protocol type from the interrogator in connection with data transferred from the interrogator to the GDLP. This shall include the following types of protocols: (a) ground-initiated Comm-B; (b) air-initiated Comm-B; (c) air-initiated Comm-B broadcast; and (d) downlink ELM. The GDLP shall also accept the BDS code used to identify the groundinitiated Comm-B segment The GDLP shall accept control information from the interrogator indicating the status of uplink transfers and the status of the addressed Mode S aircraft GDLP to interrogator. The GDLP shall provide an indication of protocol type to the interrogator in connection with data transferred from the GDLP to the interrogator. This shall include the following types of protocols: (a) Comm-A interrogation; (b) Comm-A broadcast interrogation; (c) uplink ELM; and (d) ground-initiated Comm-B request. 72

73 The GDLP shall also provide the BDS code for the ground-initiated Comm-B protocol DCE operation Note. The DCE process within the XDLP acts as a peer process to the DTE. The DCE supports the operations of the DTE with the capability specified in The following requirements do not specify format definitions and flow control on the DTE/DCE interface. The specifications and definitions in ISO 8208 apply for these cases State transitions. The DCE shall operate as a State machine. Upon entering a State, the DCE shall perform the actions specified in Table 5-2. State transitions and additional action(s) shall be as specified in Table 5-3 through Table Note. The next State transition (if any) that occurs when the DCE receives a packet from the DTE is specified by Table 5-3 through Table 5-8. These tables are organized according to the hierarchy illustrated in Figure 5-2. The same transitions are defined in Table 5-9 through Table 5-12 when the DCE receives a packet from the XDCE (via the reformatting process) DISPOSITION OF PACKETS Upon receipt of a packet from the DTE, the packet shall be forwarded or not forwarded to the XDCE (via the reformatting process) according to the parenthetical instructions contained in Tables 5-3 to 5-8. If no parenthetical instruction is listed or if the parenthetical instruction indicates do not forward, the packet shall be discarded Upon receipt of a packet from the XDCE (via the reformatting process), the packet shall be forwarded or not forwarded to the DTE according to the parenthetical instructions contained in Tables 5-9 to If no parenthetical instruction is listed or if the parenthetical instruction indicates do not forward, the packet shall be discarded. 1.5 Mode S packet layer processing GENERAL REQUIREMENTS 73

74 BUFFER REQUIREMENTS ADLP buffer requirements The following requirements apply to the entire ADLP and shall be interpreted as necessary for each of the main processes (DCE, reformatting, ADCE, frame processing and SSE) The ADLP shall be capable of maintaining sufficient buffer space for fifteen SVCs: (a) maintain sufficient buffer space to hold fifteen Mode S subnetwork packets of 152 bytes each in the uplink direction per SVC for a transponder with uplink ELM capability or 28 bytes otherwise; (b) maintain sufficient buffer space to hold fifteen Mode S subnetwork packets of 160 bytes each in the downlink direction per SVC for a transponder with downlink ELM capability or 28 bytes otherwise; (c) maintain sufficient buffer space for two Mode S subnetwork INTERRUPT packets of 35 bytes each (user data field plus control information), one in each direction, for each SVC; (d) maintain sufficient resequencing buffer space for storing thirtyone Mode S subnetwork packets of 152 bytes each in the uplink direction per SVC for a transponder with uplink ELM capability or 28 bytes otherwise; and (e) maintain sufficient buffer space for the temporary storage of at least one Mode S packet of 160 bytes undergoing M-bit or S-bit processing in each direction per SVC. (f) The ADLP shall be capable of maintaining a buffer of bytes in each direction to be shared among all MSPs GDLP buffer requirements The GDLP shall be capable of maintaining sufficient buffer space for an average of 4 SVCs for each Mode S aircraft in the coverage area of the interrogators connected to it, assuming all aircraft have ELM capability CHANNEL NUMBER POOLS 74

75 The XDLP shall maintain several SVC channel number pools; the DTE/DCE (ISO 8208) interface uses one set. Its organization, structure and use shall be as defined in the ISO 8208 standard. The other channel pools shall be used on the ADCE/GDCE interface The GDLP shall manage a pool of temporary channel numbers in the range of 1 to 3, for each ground DTE/ADLP pair. Mode S CALL REQUEST packets generated by the GDLP shall contain the ground DTE address and a temporary channel number allocated from the pool of that ground DTE. The GDLP shall not reuse a temporary channel number allocated to an SVC that is still in the CALL REQUEST State. Note 1. The use of temporary channel numbers allows the GDLP to have up to three call requests in process at the same time for a particular ground DTE and ADLP combination. It also allows the GDLP or ADLP to clear a channel before the permanent channel number is assigned. Note 2. The ADLP may be in contact with multiple ground DTEs at any one time. All the ground DTEs use temporary channel numbers ranging from 1 to The ADLP shall use the ground DTE address to distinguish the temporary channel numbers used by the various ground DTEs. The ADLP shall assign a permanent channel number (in the range of 1 to 15) to all SVCs and shall inform the GDLP of the assigned number by including it in the Mode S CALL REQUEST by ADLP or Mode S CALL ACCEPT by ADLP packets. The temporary channel number shall be included in the Mode S CALL ACCEPT by ADLP together with the permanent channel number in order to define the association of these channel numbers. The ADLP shall continue to associate the temporary channel number with the permanent channel number of an SVC until the SVC is returned to the READY (p1) State, or else, while in the DATA TRANSFER (p4) State, a Mode S CALL REQUEST by GDLP packet is received bearing the same temporary channel number. A non-zero permanent channel number in the Mode S CLEAR REQUEST by ADLP, CLEAR REQUEST by GDLP, CLEAR CONFIRMATION by ADLP or CLEAR CONFIRMATION by GDLP packet shall indicate that the permanent channel number shall be used and the temporary channel 75

76 number shall be ignored. In the event that an XDLP is required to send one of these packets in the absence of a permanent channel number, the permanent channel number shall be set to zero, which shall indicate to the peer XDLP that the temporary channel number is to be used The channel number used by the DTE/DCE interface and that used by the ADCE/GDCE interface shall be assigned independently. The reformatting process shall maintain an association table between the DTE/DCE and the ADCE/GDCE channel numbers Receive ready and receive not ready conditions. The ISO 8208 interface and the ADCE/GDCE interface management procedures shall be independent operations since each system must be able to respond to separate receive ready and receive not ready indications PROCESSING OF M-BIT AND S-BIT SEQUENCE Note. M-bit processing applies to the sequencing of the DATA packet. S-bit processing applies to the sequencing of Mode S CALL REQUEST, CALL ACCEPT, CLEAR REQUEST and INTERRUPT packets M-bit processing Note. The packet size used on the DTE/DCE interface can be different from that used on the ADCE/GDCE interface M-bit processing shall be used when DATA packets are reformatted. M-bit processing shall utilize the specifications contained in the ISO 8208 standard. The M-bit sequence processing shall apply on a per channel basis. The M-bit set to 1 shall indicate that a user data field continues in the subsequent DATA packet. Subsequent packets in an M-bit sequence shall use the same header format (i.e. the packet format excluding the user data field) If the packet size for the XDCE interface is larger than that used on the DTE/DCE interface, packets shall be combined to the extent possible as dictated by the M-bit, when transmitting a Mode S DATA packet. If the packet size is smaller on the XDCE interface than that defined on the DTE/DCE interface, packets shall be fragmented to fit into the smaller Mode S packet using M-bit assembly. 76

77 A packet shall be combined with subsequent packets if the packet is filled and more packets exist in the M-bit sequence (M-bit = 1). A packet smaller than the maximum packet size defined for this SVC (partial packet) shall only be allowed when the M-bit indicates the end of an M-bit sequence. A received packet smaller than the maximum packet size with M-bit equal to 1 shall cause a reset to be generated as specified in ISO 8208 and the remainder of the sequence should be discarded In order to decrease delivery delay, reformatting shall be performed on the partial receipt of an M-bit sequence, rather than delay reformatting until the complete M-bit sequence is received S-bit processing. S-bit processing shall apply only to Mode S CALL REQUEST, CALL ACCEPT, CLEAR REQUEST and INTERRUPT packets. This processing shall be performed as specified for M-bit processing except that the packets associated with any S-bit sequence whose reassembly is not completed in Tq seconds MODE S SUBNETWORK ERROR PROCESSING FOR ISO 8208 PACKETS D-bit. If the XDLP receives a DATA packet with the D-bit set to 1, the XDLP shall send a RESET REQUEST packet to the originating DTE containing a cause code (CC) = 133 and a diagnostic code (DC) = 166. If the D-bit is set to 1 in a CALL REQUEST packet, the D-bit shall be ignored by the XDLP. The D-bit of the corresponding CALL ACCEPT packet shall always be set to 0. The use of CC is optional Q-bit. If the XDLP receives a DATA packet with the Q-bit set to 1, the XDLP shall send a RESET REQUEST packet to the originating DTE containing CC = 133 and DC = 83. The use of CC is optional Invalid priority. If the XDLP receives a call request with a connection priority value equal to 2 through 254, the XDLP shall clear the virtual circuit using DC = 66 and CC = 131. The use of CC is optional Unsupported facility. If the XDLP receives a call request with a request for a facility that it cannot support, the XDLP shall clear the virtual circuit using DC = 65 and C = 131. The use of CC is optional. 77

78 Illegal calling DTE address. If the XDLP receives a call request with an illegal calling DTE address, the XDLP shall clear the virtual circuit using DC = 68 and CC = 141. The use of CC is optional Illegal called DTE address. If the XDLP receives a call request with an illegal called DTE address, the XDLP shall clear the virtual circuit using DC = 67 and CC = 141. The use of CC is optional REFORMATTING PROCESS Note. The reformatting process is divided into two subprocesses: uplink formatting and downlink formatting. For the ADLP, the uplink process reformats Mode S packets into ISO 8208 packets and the downlink process reformats ISO 8208 packets into Mode S packets. For the GDLP, the uplink process reformats ISO 8208 packets into Mode S packets and the downlink process reformats Mode S packets into ISO 8208 packets CALL REQUEST BY ADLP Translation into Mode S packets Translated packet format. Reception by the ADLP reformatting process of an ISO 8208 CALL REQUEST packet from the local DCE shall result in the generation of corresponding Mode S CALL REQUEST by ADLP packet(s) (as determined by S-bit processing ) as follows: Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to Priority (P). This field shall be set to 0 for a low priority SVC and to 1 for a high priority SVC. The value for this field shall be obtained from the data transfer field of the priority facility of the ISO 8208 packet, and shall be set to 0 if the ISO 8208 packet does not contain the priority facility or if a priority of 255 is specified. The other fields of the priority facility shall be ignored. 78

79 Sequence number (SN). For a particular SVC, each packet shall be numbered Channel number (CH). The channel number shall be chosen from the pool of SVC channel numbers available to the ADLP. The pool shall consist of 15 values from 1 through 15. The highest available channel number shall be chosen from the pool. An available channel shall be defined as one in State p1. The correspondence between the channel number used by the Mode S subnetwork and the number used by the DTE/DCE interface shall be maintained while the channel is active Address, mobile (AM). This address shall be the mobile DTE subaddress in the range of 0 to 15. The address shall be extracted from the two least significant digits of the calling DTE address contained in the ISO 8208 packet and converted to binary representation Address, ground (AG). This address shall be the ground DTE address in the range of 0 to 255. The address shall be extracted from the called DTE address contained in the ISO 8208 packet and converted to binary representation Fill field. The fill field shall be used to align subsequent data fields on byte boundaries. When indicated as FILL:n, the fill field shall be set to a length of n bits. When indicated as FILL1: 0 or 6, the fill field shall be set to a length of 6 bits for a non-multiplexed packet in a downlink SLM frame and 0 bit for all other cases. When indicated as FILL2: 0 or 2, the fill field shall be set to a length of 0 bit for a non-multiplexed packet in a downlink SLM frame or for a multiplexing header and 2 bits for all other cases S field (S). A value of 1 shall indicate that the packet is part of an S- bit sequence with more packets in the sequence to follow. A value of 0 shall indicate that the sequence ends with this packet. FS field (FS). A value of 0 shall indicate that the packet does not contain fast select data. A value of 2 or 3 shall indicate that the packet contains fast select data. A value of 2 shall indicate normal fast select operation. A value of 3 shall indicate fast select with restricted response. An FS value of 1 shall be undefined. 79

80 First packet flag (F). This field shall be set to 0 in the first packet of an S-bit sequence and in a packet that is not part of an S-bit sequence. Otherwise it shall be set to User data length (LV). This field shall indicate the number of full bytes used in the last SLM or ELM segment User data field (UD). This field shall only be present if optional CALL REQUEST user data (maximum 16 bytes) or fast select user data (maximum 128 bytes) is contained in the ISO 8208 packet. The user data field shall be transferred from ISO 8208 packet unchanged using S-bit processing Translation into ISO 8208 packets Translation. Reception by the GDLP reformatting process of a Mode S CALL REQUEST by ADLP packet (or an S-bit sequence of packets) from the GDCE shall result in the generation of a corresponding ISO 8208 CALL REQUEST packet to the local DCE. The translation from the Mode S packet to the ISO 8208 packet shall be the inverse of the processing Called DTE, calling DTE address and length fields. The calling DTE address shall be composed of the aircraft address and the value contained in the AM field of the Mode S packet, converted to BCD. The called DTE address shall be the ground DTE address contained in the AG field of the Mode S packet, converted to BCD. The length field shall be as defined in ISO CALL REQUEST BY GDLP Translation into Mode S packets General. Reception by the GDLP reformatting process of an ISO 8208 CALL REQUEST packet from the local DCE shall result in the generation of corresponding Mode S CALL REQUEST by GDLP packet(s) (as determined by S-bit processing ( )) as follows: Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in

81 Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to Temporary channel number field (TC). This field shall be used to distinguish multiple call requests from a GDLP. The ADLP reformatting process, upon receipt of a temporary channel number, shall assign a channel number from those presently in the READY State, p Address, ground (AG). This address shall be the ground DTE address (in the range of 0 to 255. The address shall be extracted from the calling DTE address contained in the ISO 8208 packet and converted to binary representation Address, mobile (AM). This address shall be the mobile DTE subaddress in the range of 0 to 15. The address shall be extracted from the two least significant digits of the called DTE address contained in the ISO 8208 packet and converted to binary representation Translation into ISO 8208 packets Translation. Reception by the ADLP reformatting process of a Mode S CALL REQUEST by GDLP packet (or an S-bit sequence of packets) from the ADCE shall result in the generation of a corresponding ISO 8208 CALL REQUEST packet to the local DCE. The translation from the Mode S packet to the ISO 8208 packet shall be the inverse of the processing defined in with the exceptions as specified in Called DTE, calling DTE address and length fields. The called DTE address shall be composed of the aircraft address and the value contained in the AM field of the Mode S packet, converted to BCD. The calling DTE address shall be the ground DTE address contained in the AG field of the Mode S packet, converted to BCD. The length field shall be as defined in ISO CALL ACCEPT BY ADLP Translation into Mode S packets 81

82 Translated packet format. Reception by the ADLP reformatting process of an ISO 8208 CALL ACCEPT packet from the local DCE shall result in the generation of corresponding Mode S CALL ACCEPT by ADLP packet(s) (as determined by S-bit processing ) as follows: Fields shown in the packet format and not specified in the following paragraphs Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to Temporary channel number (TC). The TC value in the originating Mode S CALL REQUEST by GDLP packet shall be returned to the GDLP along with the channel number (CH) assigned by the ADLP Channel number (CH). The field shall be set equal to the channel number assigned by the ADLP as determined during the CALL REQUEST procedures for the Mode S connection Address, mobile and address, ground. The AM and AG values in the originating Mode S CALL REQUEST by GDLP packet shall be returned in these fields. When present, DTE addresses in the ISO 8208 CALL ACCEPT packet shall be ignored Translation into ISO 8208 packets Translation. Reception by the GDLP reformatting process of a Mode S CALL ACCEPT by ADLP packet (or an S-bit sequence of packets) from the GDCE shall result in the generation of a corresponding ISO 8208 CALL ACCEPT packet to the local DCE. The translation from the Mode S packet to the ISO 8208 packet shall be the inverse of the processing Called DTE, calling DTE address and length fields. Where present, the called DTE address shall be composed of the aircraft address and the value contained in the AM field of the Mode S packet, converted to BCD. Where present, the calling DTE address shall be the ground DTE address contained in the AG field of the 82

83 Mode S packet, converted to BCD. The length field shall be as defined in ISO CALL ACCEPT BY GDLP Translation into Mode S packets Translated packet format. Reception by the GDLP reformatting process of an ISO 8208 CALL ACCEPT packet from the local DCE shall result in the generation of corresponding Mode S CALL ACCEPT by GDLP packet(s) (as determined by S-bit processing) as follows: Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to Address, mobile and address, ground. The AM and AG values in the originating Mode S CALL REQUEST by ADLP packet shall be returned in these fields. When present, DTE addresses in the ISO 8208 CALL ACCEPT packet shall be ignored Translation into ISO 8208 packets Translation. Reception by the ADLP reformatting process of a Mode S CALL ACCEPT by GDLP packet (or an S-bit sequence of packets) from the ADCE shall result in the generation of a corresponding ISO 8208 CALL ACCEPT packet to the local DCE. The translation from the Mode S packet to the ISO 8208 packet shall be the inverse of the processing Called DTE, calling DTE address and length fields. Where present, the calling DTE address shall be composed of the aircraft address and the value contained in the AM field of the Mode S packet, converted to BCD. Where present, the called DTE address shall be the ground DTE address contained in the AG field of the Mode S packet, converted to BCD. The length field shall be as defined in ISO

84 CLEAR REQUEST BY ADLP Translation into Mode S packets Translated packet format. Reception by the ADLP reformatting process of an ISO 8208 CLEAR REQUEST packet from the local DCE shall result in the generation of a corresponding Mode S CLEAR REQUEST by ADLP packet(s) (as determined by S-bit processing ) as follows: Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Channel number (CH): If a channel number has been allocated during the call acceptance phase, then CH shall be set to that value, otherwise it shall be set to zero Temporary channel (TC): If a channel number has been allocated during the call acceptance phase, then TC shall be set to zero, otherwise it shall be set to the value used in the CALL REQUEST by GDLP Supervisory type (ST). This field shall be set to Address, ground or address, mobile. The AG and AM values in the originating Mode S CALL REQUEST by ADLP or CALL REQUEST by GDLP packets shall be returned in these fields. When present, DTE addresses in the ISO 8208 CLEAR REQUEST packet shall be ignored Clearing cause (CC) and diagnostic code (DC) fields. These fields shall be transferred without modification from the ISO 8208 packet to the Mode S packet when the DTE has initiated the clear procedure. If the XDLP has initiated the clear procedure, the clearing cause field and diagnostic field shall be as defined in the State tables for the DCE and XDCE -The coding and definition of these fields shall be as specified in ISO Translation into ISO 8208 packets Translation. Reception by the GDLP reformatting process of a Mode S CLEAR REQUEST by ADLP packet (or an S-bit sequence of 84

85 packets) from the local GDCE shall result in the generation of a corresponding ISO 8208 CLEAR REQUEST packet to the local DCE. The translation from the Mode S packet to the ISO 8208 packet shall be the inverse of the processing Called DTE, calling DTE and length fields. These fields shall be omitted in the ISO 8208 CLEAR REQUEST packet Clearing cause field. This field shall be set taking account of CLEAR REQUEST BY GDLP Translation into Mode S packets Translated packet format. Reception by the GDLP reformatting process of an ISO 8208 CLEAR REQUEST packet from the local DCE shall result in the generation of corresponding Mode S CLEAR REQUEST by GDLP packet(s) (as determined by S-bit processing )) as follows: Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Channel number (CH): If a channel number has been allocated during the call acceptance phase, then CH shall be set to that value, otherwise it shall be set to zero Temporary channel (TC): If a channel number has been allocated during the call acceptance phase, then TC shall be set to zero, otherwise it shall be set to the value used in the CALL REQUEST by GDLP Supervisory type (ST). This field shall be set to Translation into ISO 8208 packets Translation. Reception by the ADLP reformatting process of a Mode S CLEAR REQUEST by GDLP packet (or an S-bit sequence of packets) from the local ADCE shall result in the generation of a corresponding ISO 8208 CLEAR REQUEST packet to the local 85

86 DCE. The translation from the Mode S packet to the ISO 8208 packet shall be the inverse of the processing defined in Called DTE, calling DTE and length fields. These fields shall be omitted in the ISO 8208 CLEAR REQUEST packet DATA Translation into Mode S packets Translated packet format. Reception by the XDLP reformatting process of ISO 8208 DATA packet(s) from the local DCE shall result in the generation of corresponding Mode S DATA packet(s) as determined by M-bit processing as follows: Data packet type (DP). This field shall be set to M field (M). A value of 1 shall indicate that the packet is part of an M-bit sequence with more packets in the sequence to follow. A value of 0 shall indicate that the sequence ends with this packet. The appropriate value shall be placed in the M-bit field of the Mode S packet Sequence number (SN). The sequence number field shall be numbered Packet send sequence number (PS). The packet send sequence number field shall be set as specified in Packet receive sequence number (PR). The packet receive sequence number field shall be set as specified in Channel number (CH). The channel number field shall contain the Mode S channel number that corresponds to the incoming ISO 8208 DATA packet channel number User data length (LV). This field shall indicate the number of full bytes used in the last SLM or ELM segment Fill (FILL1). This field shall be set as specified in User data (UD). The user data shall be transferred from the ISO 8208 packet to the Mode S packet utilizing the M-bit packet assembly processing as required. 86

87 Translation into ISO 8208 packets. Reception by the XDLP reformatting process of Mode S DATA packet(s) from the local XDCE shall result in the generation of corresponding ISO 8208 DATA packet(s) to the local DCE. The translation from Mode S packet(s) to the ISO 8208 packet(s) shall be the inverse of the processing defined in INTERRUPT Translation into Mode S packets Translated packet format. Reception by the XDLP reformatting process of an ISO 8208 INTERRUPT packet from the local DCE shall result in the generation of corresponding Mode S INTERRUPT packet(s) (as determined by S-bit processing ( )) as follows: Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to User data length (LV). This field shall be set as specified in User data (UD). The user data shall be transferred from the ISO 8208 packet to the Mode S packet using the S-bit packet reassembly processing as required. The maximum size of the user data field for an INTERRUPT packet shall be 32 bytes Translation into ISO 8208 packets. Reception by the XDLP reformatting process of Mode S INTERRUPT packet(s) from the local XDCE shall result in the generation of a corresponding ISO 8208 INTERRUPT packet to the local DCE. The translation from the Mode S packet(s) to the ISO 8208 packet shall be the inverse of the processing defined in INTERRUPT CONFIRMATION Translation into Mode S packets 87

88 Translated packet format. Reception by the XDLP reformatting process of an ISO 8208 INTERRUPT CONFIRMATION packet from the local DCE shall result in the generation of a corresponding Mode S INTERRUPT CONFIRMATION packet as follows: Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to Supervisory subset (SS). This field shall be set to Translation into ISO 8208 packets. Reception by the XDLP reformatting process of a Mode S INTERRUPT CONFIRMATION packet from the local XDCE shall result in the generation of a corresponding ISO 8208 INTERRUPT CONFIRMATION packet to the local DCE. The translation from the Mode S packet to the ISO 8208 packet shall be the inverse of the processing defined in RESET REQUEST Translation into Mode S packets Translated packet format. Reception by the XDLP reformatting process of an ISO 8208 RESET REQUEST packet from the local DCE shall result in the generation of a corresponding Mode S RESET REQUEST packet as follows: Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to 1. 88

89 Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to Reset cause code (RC) and diagnostic code (DC). The reset cause and diagnostic codes used in the Mode S RESET REQUEST packet shall be as specified in the ISO 8208 packet when the reset procedure is initiated by the DTE. If the reset procedure originates with the DCE, the DCE State tables shall specify the diagnostic fields coding. In this case, bit 8 of the reset cause field shall be set to Translation into ISO 8208 packets. Reception by the XDLP reformatting process of a Mode S RESET packet from the local XDCE shall result in the generation of a corresponding ISO 8208 RESET packet to the local DCE. The translation from the Mode S packet to the ISO 8208 packet shall be the inverse of the processing defined in ISO 8208 RESTART REQUEST to Mode S CLEAR REQUEST. The receipt of an ISO 8208 RESTART REQUEST from the local DCE shall result in the reformatting process generating a Mode S CLEAR REQUEST by ADLP or Mode S CLEAR REQUEST by GDLP for all SVCs associated with the requesting DTE. The fields of the Mode S CLEAR REQUEST packets shall be set as specified in PACKETS LOCAL TO THE MODE S SUBNETWORK MODE S RECEIVE READY Packet format. The Mode S RECEIVE READY packet arriving from an XDLP is not related to the control of the DTE/DCE interface and shall not cause the generation of an ISO 8208 packet. The format of the packet shall be as follows: Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to Packet receive sequence number (PR). This field shall be set as specified in

90 MODE S RECEIVE NOT READY Packet format. The Mode S RECEIVE NOT READY packet arriving from an XDLP is not related to the control of the DTE/DCE interface and shall not cause the generation of an ISO 8208 packet. The format of the packet shall be as follows: Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in 1.6. The packet shall be processed as specified in Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to Packet receive sequence number (PR). This field shall be set as specified in MODE S ROUTE Packet format. The format for the packet shall be as follows: Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in The packet shall only be generated by the GDLP. It shall be processed by the ADLP as specified in regulation VVVV and shall have a maximum size Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to Option flag (OF). This field shall indicate the presence of the optional data length (ODL) and optional data (OD) fields. OF shall be set to 1 if ODL and OD are present. Otherwise it shall be set to 0. 90

91 Initialization bit (IN). This field shall indicate the requirement for subnetwork initialization. It shall be set by the GDLP as specified in regulation VVVB) Route table length (RTL). This field shall indicate the size of the route table, expressed in bytes Route table (RT) Contents. This table shall consist of a variable number of entries each containing information specifying the addition or deletion of entries in the II code-dte cross-reference table Entries. Each entry in the route table shall consist of the II code, a list of up to 8 ground DTE addresses, and a flag indicating whether the resulting II code-dte pairs shall be added or deleted from the II code-dte cross-reference table. A route table entry shall be coded as follows: Interrogator identifier (II). This field shall contain the 4-bit II code Add/delete flag (AD). This field shall indicate whether the II code- DTE pairs shall be added (AD = 1) or deleted (AD = 0) from the II code-dte cross-reference table Number of DTE addresses (ND). This field shall be expressed in binary in the range from 0 to 7 and shall indicate the number of DTE addresses present in DAL minus 1 (in order to allow from 1 to 8 DTE addresses) DTE address list (DAL). This list shall consist of up to 8 DTE addresses, expressed in 8-bit binary representation Optional data length (ODL). This field shall contain the length in bytes of the following OD field Optional data (OD). This variable length field shall contain optional data MODE S CLEAR CONFIRMATION BY ADLP Packet format. The format for this packet shall be as follows: 91

92 Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in and This packet shall be processed as specified in Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Channel number (CH): If a channel number has been allocated during the call acceptance phase, then CH shall be set to that value, otherwise it shall be set to zero Temporary channel (TC): If a channel number has been allocated during the call acceptance phase, then TC shall be set to zero, otherwise it shall be set to the value used in the CALL REQUEST by GDLP Supervisory type (ST). This field shall be set to MODE S CLEAR CONFIRMATION BY GDLP Packet format. The format for this packet shall be as follows: Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in and This packet shall be processed as specified in Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Channel number (CH): If a channel number has been allocated during the call acceptance phase, then CH shall be set to that value, otherwise it shall be set to zero. 92

93 Temporary channel (TC): If a channel number has been allocated during the call acceptance phase, then TC shall be set to zero, otherwise it shall be set to the value used in the CALL REQUEST by GDLP Supervisory type (ST). This field shall be set to MODE S RESET CONFIRMATION Packet format. The format for this packet shall be as follows: Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in This packet shall be processed as specified in Table Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to MODE S REJECT Packet format. The format for this packet shall be as follows: Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in This packet shall be processed as specified in Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to Supervisory type (ST). This field shall be set to Supervisory subset (SS). This field shall be set to Packet receive sequence number (PR). This field shall be set as specified in XDCE operation 93

94 Note. The ADCE process within the ADLP acts as a peer process to the GDCE process in the GDLP State transitions. The XDCE shall operate as a State machine. Upon entering a State, the XDCE shall perform the actions specified in Table State transition and additional action(s) shall be as specified in Table through Table Note 1. The next State transition (if any) that occurs when the XDCE receives a packet from the peer XDCE is specified by Table 5-15 through Table The same transitions are defined in Table 5-20 through Table 5-22 when the XDCE receives a packet from the DCE (via the reformatting process). Note 2. The XDCE State hierarchy is the same as for the DCE as presented in Figure 5-2, except that States r2, r3 and p5 are omitted DISPOSITION OF PACKETS Upon receipt of a packet from the peer XDCE, the packet shall be forwarded or not forwarded to the DCE (via the reformatting process) according to the parenthetical instructions contained in Tables to If no parenthetical instruction is listed or if the parenthetical instruction indicates do not forward the packet shall be discarded Upon receipt of a packet from the DCE (via the reformatting process), the packet shall be forwarded or not forwarded to the peer XDCE according to the parenthetical instructions contained in Tables to If no parenthetical instruction is listed or if the parenthetical instruction indicates do not forward the packet shall be discarded SVC CALL SETUP AND CLEAR PROCEDURE Setup procedures. Upon receipt of a CALL REQUEST from the DCE or peer XDCE, the XDLP shall determine if sufficient resources exist to operate the SVC. This shall include: sufficient buffer space (refer to for buffer requirements) and an available p1 State SVC. Upon acceptance of the CALL REQUEST from the DCE (via the reformatting process), the Mode S CALL REQUEST packet shall be forwarded to frame processing. Upon acceptance of a Mode S CALL REQUEST from the peer XDCE (via frame processing), the Mode S CALL REQUEST shall be sent to the reformatting process Aborting a call request. If the DTE and/or the peer XDCE abort a call before they have received a CALL ACCEPT packet, they shall indicate 94

95 this condition by issuing a CLEAR REQUEST packet. Procedures for handling these cases shall be as specified in Table and Table VIRTUAL CALL CLEARING If the XDCE receives a Mode S CALL REQUEST from the reformatting process that it cannot support, it shall initiate a Mode S CLEAR REQUEST packet that is sent to the DCE (via the reformatting process) for transfer to the DTE (the DCE thus enters the DCE CLEAR REQUEST to DTE State, p7) If the XDCE receives a Mode S CALL REQUEST packet from the peer XDCE (via frame processing) which it cannot support, it shall enter the State p A means shall be provided to advise the DTE whether an SVC has been cleared due to the action of the peer DTE or due to a problem within the sub network itself The requirement of shall be satisfied by setting bit 8 of the cause field to 1 to indicate that the problem originated in the Mode S sub network and not in the DTE. The diagnostic and cause codes shall be set as follows: a. no channel number available, DC = 71, CC = 133; b. buffer space not available, DC = 71, CC = 133; c. DTE not operational, DC = 162, CC = 141; and d. link failure, DC = 225, CC = If the ADLP receives a Mode S ROUTE packet with the IN bit set to ONE, the ADLP shall perform local initialization by clearing Mode S SVCs associated with the DTE addresses contained in the ROUTE packet. If the GDLP receives a search request (Table 5-23) from an ADLP, the GDLP shall perform local initialization by clearing Mode S SVCs associated with that ADLP. Local initialization shall be accomplished by: (a) releasing all allocated resources associated with these SVCs (including the resequencing buffers); (b) returning these SVCs to the ADCE ready State (p1); and (c) sending Mode S CLEAR REQUEST packets for these SVCs to the DCE (via the reformatting process) for transfer to the DTE. 95

96 Clear confirmation. When the XDCE receives a Mode S CLEAR CONFIRMATION packet, the remaining allocated resources to manage the SVC shall be released (including the resequencing buffers) and the SVC shall be returned to the p1 State. Mode S CLEAR CONFIRMATION packets shall not be transferred to the reformatting process Clear collision. A clear collision occurs at the XDCE when it receives a Mode S CLEAR REQUEST packet from the DCE (via the reformatting process) and then receives a Mode S CLEAR REQUEST packet from the peer XDCE (or vice versa). In this event, the XDCE does not expect to receive a Mode S CLEAR CONFIRMATION packet for this SVC and shall consider the clearing complete Packet processing. The XDCE shall treat an S-bit sequence of Mode S CALL REQUEST, CALL ACCEPT and CLEAR REQUEST packets as a single entity DATA TRANSFER AND INTERRUPT PROCEDURES GENERAL PROVISIONS Data transfer and interrupt procedures shall apply independently to each SVC. The contents of the user data field shall be passed transparently to the DCE or to the peer XDCE. Data shall be transferred in the order dictated by the sequence numbers assigned to the data packets To transfer DATA packets, the SVC shall be in a FLOW CONTROL READY State (d1) MODE S PACKET SIZE The maximum size of Mode S packets shall be 152 bytes in the uplink direction and 160 bytes in the downlink direction for installations that have full uplink and downlink ELM capability. The maximum downlink packet size for level four transponders with less than 16 segment downlink ELM capability shall be 10 bytes times the maximum number of downlink ELM segments that the transponder specifies in its data link capability report. If there is no ELM capability, the maximum Mode S packet size shall be 28 bytes. 96

97 The Mode S sub network shall allow packets of less than the maximum size to be transferred FLOW CONTROL WINDOW SIZE The flow control window size of the Mode S sub network shall be independent of that used on the DTE/DCE interface. The Mode S sub network window size shall be 15 packets in the uplink and downlink directions SVC FLOW CONTROL Flow control shall be managed by means of a sequence number for received packets (PR) and one for packets that have been sent (PS). A sequence number (PS) shall be assigned for each Mode S DATA packet generated by the XDLP for each SVC. The first Mode S DATA packet transferred by the XDCE to frame processing when the SVC has just entered the flow control ready State shall be numbered zero. The first Mode S packet received from the peer XDCE after an SVC has just entered the flow control ready State shall be numbered zero. Subsequent packets shall be numbered consecutively A source of Mode S DATA packets (the ADCE or GDCE) shall not send (without permission from the receiver) more Mode S DATA packets than would fill the flow control window. The receiver shall give explicit permission to send more packets The permission information shall be in the form of the next expected packet sequence number and shall be denoted PR. If a receiver wishes to update the window and it has data to transmit to the sender, a Mode S DATA packet shall be used for information transfer. If the window must be updated and no data are to be sent, a Mode S RECEIVE READY (RR) or Mode S RECEIVE NOT READY (RNR) packet shall be sent. At this point, the sliding window shall be moved to begin at the new PR value. The XDCE shall now be authorized to transfer more packets without acknowledgement up to the window limit When the sequence number (PS) of the next Mode S DATA packet to be sent is in the range PR PS PR + 14 (modulo 16), the sequence number shall be defined to be in the window and the XDCE shall be authorized to transmit the packet. Otherwise, the sequence number (PS) of the packet shall be defined to be outside 97

98 the window and the XDCE shall not transmit the packet to the peer XDCE When the sequence number (PS) of the packet received is next in sequence and within the window, the XDCE shall accept this packet. Receipt of a packet with a PS: a) outside the window; or b) out of sequence; or c) not equal to 0 for the first data packet after entering FLOW CONTROL READY State (d1); shall be considered an error ( ) The receipt of a Mode S DATA packet with a valid PS number (i.e. the next PS in sequence) shall cause the lower window PR to be changed to that PS value plus 1. The packet receive sequence number (PR) shall be conveyed to the originating XDLP by a Mode S DATA, RECEIVE READY, RECEIVE NOT READY, or REJECT packet. A valid PR value shall be transmitted by the XDCE to the peer XDCE after the receipt of 8 packets provided that sufficient buffer space exists to store 15 packets. Incrementing the PR and PS fields shall be performed using modulo 16 arithmetic A copy of a packet shall be retained until the user data has been successfully transferred. Following successful transfer, the PS value shall be updated The PR value for user data shall be updated as soon as the required buffer space for the window (as determined by flow control management) is available within the DCE Flow control management shall be provided between the DCE and XDCE INTERRUPT PROCEDURES FOR SWITCHED VIRTUAL CIRCUITS If user data is to be sent via the Mode S sub-network without following the flow control procedures, the interrupt procedures shall be used. The interrupt procedure shall have no effect on the normal data packet and flow control procedures. An interrupt packet shall be delivered to the DTE (or the transponder or interrogator interface) at or before the point in the stream of data at which the interrupt was generated. The processing of a Mode S INTERRUPT packet shall occur as soon as it is received by the XDCE The XDCE shall treat an S-bit sequence of Mode S INTERRUPT packets as a single entity. 98

99 Interrupt processing shall have precedence over any other processing for the SVC occurring at the time of the interrupt The reception of a Mode S INTERRUPT packet before the previous interrupt of the SVC has been confirmed (by the receipt of a Mode S INTERRUPT CONFIRMATION packet) shall be defined as an error. The error results in a reset (see Table 5-18) RECEIVE READY PROCEDURE The Mode S RECEIVE READY packet shall be sent if no Mode S DATA packets (that normally contain the updated PR value) are available for transmittal and it is necessary to transfer the latest PR value. It also shall be sent to terminate a receiver not ready condition Receipt of the Mode S RECEIVE READY packet by the XDCE shall cause the XDCE to update its value of PR for the outgoing SVC. It shall not be taken as a demand for retransmission of packets that have already been transmitted and are still in the window Upon receipt of the Mode S RECEIVE READY packet, the XDCE shall go into the ADLP(GDLP) RECEIVE READY State (g1) RECEIVE NOT READY PROCEDURE The Mode S RECEIVE NOT READY packet shall be used to indicate a temporary inability to accept additional DATA packets for the given SVC. The Mode S RNR condition shall be cleared by the receipt of a Mode S RR packet or a Mode S REJECT packet When the XDCE receives a Mode S RECEIVE NOT READY packet from the peer XDCE, it shall update its value of PR for the SVC and stop transmitting Mode S DATA packets on the SVC to the XDLP. The XDCE shall go into the ADLP(GDLP) RECEIVE NOT READY State (g2) The XDCE shall transmit a Mode S RECEIVE NOT READY packet to the peer XDCE if it is unable to receive from the peer XDCE any more Mode S DATA packets on the indicated SVC. Under these conditions, the XDCE shall go into the ADCE(GDCE) RECEIVE NOT READY State (f2) RESET PROCEDURE When the XDCE receives a Mode S RESET REQUEST packet from either the peer XDCE or the DCE (via the reformatting process) or due to 99

100 an error condition performs its own reset, the following actions shall be taken: a) those Mode S DATA packets that have been transmitted to the peer XDCE shall be removed from the window; b) those Mode S DATA packets that are not transmitted to the peer XDCE but are contained in an M-bit sequence for which some packets have been transmitted shall be deleted from the queue of DATA packets awaiting transmission; c) those Mode S DATA packets received from the peer XDCE that are part of an incomplete M-bit sequence shall be discarded; d) the lower window edge shall be set to 0 and the next packet sent shall have a sequence number (PS) of 0; e) any outstanding Mode S INTERRUPT packets to or from the peer XDCE shall be left unconfirmed; f) any Mode S INTERRUPT packet awaiting transfer shall be discarded; g) data packets awaiting transfer shall not be discarded (unless they are part of a partially transferred M-bit sequence); and h) the transition to d1 shall also include a transition to i1, j1, f 1 and g The reset procedure shall apply to the DATA TRANSFER State (p4). The error procedure in Table 5-16 shall be followed. In any other State the reset procedure shall be abandoned REJECT PROCEDURE When the XDCE receives a Mode S DATA packet from the peer XDCE with incorrect format or whose packet sequence number (PS) is not within the defined window (Table 5-19) or is out of sequence, it shall discard the received packet and send a Mode S REJECT packet to the peer XDCE via frame processing. The Mode S REJECT packet shall indicate a value of PR for which retransmission of the Mode S DATA packets is to begin. The XDCE shall discard subsequent out-of-sequence Mode S DATA packets whose receipt occurs while the Mode S REJECT packet response is still outstanding When the XDCE receives a Mode S REJECT packet from the peer XDCE, it shall update its lower window value with the new value of PR and begin to (re)transmit packets with a sequence number of PR Reject indications shall not be transferred to the DCE. If the ISO 8208 interface supports the reject procedures, the reject indications occurring on the ISO 8208 interface shall not be transferred between the DCE and the XDCE. 100

101 1.6.9 PACKET RESEQUENCING AND DUPLICATE SUPPRESSION Resequencing. Resequencing shall be performed independently for the uplink and downlink transfers of each Mode S SVC. The following variables and parameters shall be used: SNR A 6-bit variable indicating the sequence number of a received packet on a specific SVC. It is contained in the SN field of the packet ( ). NESN The next expected sequence number following a series of consecutive sequence numbers. HSNR The highest value of SNR in the resequencing window. Tq Resequencing timers (see Tables 5-1 and 5-13) associated with a specific SVC. All operations involving the sequence number (SN) shall be performed modulo Duplication window. The range of SNR values between NESN 32 and NESN 1 inclusive shall be denoted the duplication window Resequencing window. The range of SNR values between NESN + 1 and NESN + 31 inclusive shall be denoted the resequencing window. Received packets with a sequence number value in this range shall be stored in the resequencing window in sequence number order TRANSMISSION FUNCTIONS For each SVC, the first packet sent to establish a connection (the first Mode S CALL REQUEST or first Mode S CALL ACCEPT packet) shall cause the value of the SN field to be initialized to zero. The value of the SN field shall be incremented after the transmission (or retransmission) of each packet The maximum number of unacknowledged sequence numbers shall be 32 consecutive SN numbers. Should this condition be reached, then it shall be treated as an error and the channel cleared RECEIVE FUNCTIONS Resequencing. The resequencing algorithm shall maintain the variables HSNR and NESN for each SVC. NESN shall be initialized to 0 for all SVCs and shall be reset to 0 when the SVC re-enters the channel number pool. 101

102 Processing of packets within the duplication window. If a packet is received with a sequence number value within the duplication window, the packet shall be discarded Processing of packets within the resequencing window. If a packet is received with a sequence number within the resequencing window, it shall be discarded as a duplicate if a packet with the same sequence number has already been received and stored in the resequencing window. Otherwise, the packet shall be stored in the resequencing window. Then, if no Tq timers are running, HSNR shall be set to the value of SNR for this packet and a Tq timer shall be started with its initial value (Tables 5-1 and 5-13). If at least one Tq timer is running, and SNR is not in the window between NESN and HSNR + 1 inclusive, a new Tq timer shall be started and the value of HSNR shall be updated. If at least one Tq timer is running, and SNR for this packet is equal to HSNR + 1, the value of HSNR shall be updated Release of packets to the XDCE. If a packet is received with a sequence number equal to NESN, the following procedure shall be applied: a) the packet and any packets already stored in the resequencing window up to the next missing sequence number shall be passed to the XDCE; b) NESN shall be set to 1 + the value of the sequence number of the last packet passed to the XDCE; and c) the Tq timer associated with any of the released packets shall be stopped Tq timer expiration. If a Tq timer expires, the following procedure shall be applied: (a) NESN shall be incremented until the next missing sequence number is detected after that of the packet associated with the Tq timer that has expired (b) any stored packets with sequence numbers that are no longer in the resequencing window shall be forwarded to the XDCE except that an incomplete S-bit sequence shall be discarded; and (c) the Tq timer associated with any released packets shall be stopped. 1.7 Mode S specific services processing 102

103 Mode S specific services shall be processed by an entity in the XDLP termed the Mode S specific services entity (SSE). Transponder registers shall be used to convey the information specified in Table The data structuring of the registers in Table 5-24 shall be implemented in such a way that interoperability is ensured. Note 1. The data formats and protocols for messages transferred via Mode S specific services are specified in the Technical Provisions for Mode S Services and Extended Squitter (Doc 9871) (in preparation). Note 2. Uniform implementation of the data formats and protocols for messages transferred via Mode S specific services will ensure interoperability. Note 3. This section describes the processing of control and message data received from the Mode S specific services interface. Note 4. Control data consists of information permitting the determination of, for example, message length, BDS code used to access the data format for a particular register, and aircraft address ADLP PROCESSING DOWNLINK PROCESSING Specific services capability. The ADLP shall be capable of receiving control and message data from the Mode S specific services interface(s) and sending delivery notices to this interface. The control data shall be processed to determine the protocol type and the length of the message data. When the message or control data provided at this interface are erroneous (i.e. incomplete, invalid or inconsistent), the ADLP shall discard the message and deliver an error report at the interface. Note. The diagnostic content and error reporting mechanism are a local issue Broadcast processing. The control and message data shall be used to format the Comm-B broadcast message as specified in and transferred to the transponder. 103

104 GICB processing. The 8-bit BDS code shall be determined from the control data. The 7-byte register content shall be extracted from the received message data. The register content shall be transferred to the transponder, along with an indication of the specified register number. A request to address one of the airinitiated Comm-B registers or the airborne collision avoidance system (ACAS) active resolution advisories register shall be discarded. The assignment of registers shall be as specified in Table Note. Provision of the data available in transponder registers 40, 50 and 60 {HEX} has been mandated in some ICAO m Regions in support of ATM applications MSP processing The MSP message length, channel number (M/CH) and optionally the interrogator identifier (II) code shall be determined from the control data. The MSP message content shall be extracted from the received message data. If the message length is 26 bytes or less, the SSE shall format an air-initiated Comm-B message for transfer to the transponder using the short form MSP packet.if the message length is 27 to 159 bytes and the transponder has adequate downlink ELM capability, the SSE shall format an ELM message for transfer using the short form MSP packet. If the message length is 27 to 159 bytes and the transponder has a limited downlink ELM capability, the SSE shall format multiple long form MSP packets using ELM messages, as required utilizing the L-bit and M/SN fields for association of the packets. If the message length is 27 to 159 bytes and the transponder does not have downlink ELM capability, the SSE shall format multiple long form MSP packets using air initiated Comm-B messages, as required utilizing the L-bit and M/SN fields for association of the packets. Different frame types shall never be used in the delivery of an MSP message. Messages longer than 159 bytes shall be discarded. The assignment of downlink MSP channel numbers shall be as specified in Table For an MSP, a request to send a packet shall cause the packet to be multisite-directed to the interrogator which II code is specified in control data. If no II code is specified, the packet shall be down- 104

105 linked using the air-initiated protocol. A message delivery notice for this packet shall be provided to the Mode S specific interface when the corresponding close-out(s) have been received from the transponder. If a close-out has not been received from the transponder in Tz seconds, as specified in Table 5-1, the MSP packet shall be discarded. This shall include the cancellation in the transponder of any frames associated with this packet. A delivery failure notice for this message shall be provided to the Mode S specific services interface UPLINK PROCESSING Note. This section describes the processing of Mode S specific services messages received from the transponder Specific services capability. The ADLP shall be capable of receiving Mode S specific services messages from the transponder via frame processing. The ADLP shall be capable of delivering the messages and the associated control data at the specific services interface. When the resources allocated at this interface are insufficient to accommodate the output data, the ADLP shall discard the message and deliver an error report at this interface. Note. The diagnostic content and the error reporting mechanism are a local issue Broadcast processing. If the received message is a broadcast Comm- A, as indicated by control data received over the transponder/adlp interface, the broadcast ID and user data (1.7.5) shall be forwarded to the Mode S specific services interface ( ) along with the control data that identifies this as a broadcast message. The assignment of uplink broadcast identifier numbers shall be as specified in Table MSP processing. If the received message is an MSP, as indicated by the packet format header (1.7.3), the user data field of the received MSP packet shall be forwarded to the Mode S specific services interface ( ) together with the MSP channel number (M/CH), the IIS subfield ( ) together with control data that identifies this as an MSP message. L-bit processing shall be performed as specified in The assignment of uplink MSP channel numbers shall be as specified in Table

106 1.7.2 GDLP PROCESSING UPLINK PROCESSING Specific services capability. The GDLP shall be capable of receiving control and message data from the Mode S specific services interface(s) ( ) and sending delivery notices to the interface(s). The control data shall be processed to determine the protocol type and the length of the message data Broadcast processing. The GDLP shall determine the interrogator(s), broadcast azimuths and scan times from the control data and format the broadcast message for transfer to the interrogator(s) GICB processing. The GDLP shall determine the register number and the aircraft address from the control data. The aircraft address and BDS code shall be passed to the interrogator as a request for a ground-initiated Comm-B MSP processing. The GDLP shall extract from the control data the message length, the MSP channel number (M/CH) and the aircraft address, and obtain the message content from the message data. If the message length is 27 bytes or less, the SSE shall format a Comm- A message for transfer to the interrogator using the short form MSP packet. If the message length is 28 to 151 bytes and the transponder has uplink ELM capability, the SSE shall format an ELM message for transfer to the interrogator using the short form MSP packet. If the message length is 28 to 151 bytes and the transponder does not have uplink ELM capability, the SSE shall format multiple long form MSP packets ( ) utilizing the L-bit and the M/SN fields for association of the packets. Messages longer than 151 bytes shall be discarded. The interrogator shall provide a delivery notice to the Mode S specific services interface(s) indicating successful or unsuccessful delivery, for each uplinked packet. 106

107 DOWNLINK PROCESSING Specific services capability. The GDLP shall be capable of receiving Mode S specific services messages from the interrogator via frame processing Broadcast processing. If the received message is a broadcast Comm- B, as indicated by the interrogator/gdlp interface, the GDLP shall: (a) generate control data indicating the presence of a broadcast message and the 24-bit address of the aircraft from which the message was received; (b) append the 7-byte MB field of the broadcast Comm-B; and (c) forward this data to the Mode S specific services interface(s) GICB processing. If the received message is a GICB, as indicated by the interrogator/gdlp interface, the GDLP shall: (a) generate control data indicating the presence of a GICB message, the register number and the 24-bit address of the aircraft from which the message was received; (b) append the 7-byte MB field of the GICB; and (c) forward this data to the Mode S specific services interface(s) MSP processing. If the received message is an MSP as indicated by the packet format header, the GDLP shall: (a) generate control data indicating the transfer of an MSP, the length of the message, the MSP channel number (M/CH) and the 24-bit address of the aircraft from which the message was received; (b) append the user data field of the received MSP packet; and (c) forward this data to the Mode S specific services interface(s). L-bit processing shall be performed as specified in MSP PACKET FORMATS Short form MSP packet. The format for this packet shall be as follows: 107

108 Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to MSP channel number (M/CH). The field shall be set to the channel number derived from the SSE control data Fill field (FILL1:0 or 6). The fill length shall be 6 bits for a downlink SLM frame. Otherwise the fill length shall be User data (UD). The user data field shall contain message data received from the Mode S specific services interface Long form MSP packet. The format for this packet shall be as follows: Fields shown in the packet format and not specified in the following paragraphs shall be set as specified in and Data packet type (DP). This field shall be set to MSP packet type (MP). This field shall be set to Supervisory packet (SP). This field shall be set to L field (L). A value of 1 shall indicate that the packet is part of an L- bit sequence with more packets in the sequence to follow. A value of 0 shall indicate that the sequence ends with this packet MSP sequence number field (M/SN). This field shall be used to detect duplication in the delivery of L-bit sequences. The first packet in an L-bit sequence shall be assigned a sequence number of 0. Subsequent packets shall be numbered sequentially. A packet received with the same sequence number as the previously received packet shall be discarded. 108

109 1.7.4 L-bit processing. L-bit processing shall be performed only on the long form MSP packet and shall be performed as specified for M-bit processing except as specified in the following paragraphs Upon receipt of a long form MSP packet, the XDLP shall construct the user data field by: (a) verifying that the packet order is correct using the M/SN field (b) assuming that the user data field in the MSP packet is the largest number of integral bytes that is contained within the frame; (c) associating each user data field in an MSP packet received with a previous user data field in an MSP packet that has an L-bit value of 1; and Note. Truncation of the user data field is not permitted as this is treated as an error condition. (d) if an error is detected in the processing of an MSP packet, the packet shall be discarded In the processing of an L-bit sequence, the XDLP shall discard any MSP packets that have duplicate M/SN values. The XDLP shall discard the entire L-bit sequence if a long form MSP packet is determined to be missing by use of the M/SN field The packets associated with any L-bit sequence whose reassembly is not completed in Tm seconds (Tables 5-1 and 5-13) shall be discarded BROADCAST FORMAT Uplink broadcast. The format of the broadcast Comm-A shall be as follows: The 83-bit uplink broadcast shall be inserted in an uplink Comm-A frame. The MA field of the Comm-A frame shall contain the broadcast identifier specified in Table 5-23 in the first 8 bits, followed by the first 48 user data bits of the broadcast message. The last 27 user data bits of the broadcast message shall be placed in the 27 bits immediately following the UF field of the Comm-A frame Downlink broadcast. The format of broadcast Comm-B shall be as follows: The 56-bit downlink broadcast message shall be inserted in the MB field of the broadcast Comm-B. The MB field shall contain the 109

110 broadcast identifier specified in Table 5-23 in the first 8 bits, followed by the 48 user data bits. 1.8 Mode S subnetwork management INTERROGATOR LINK DETERMINATION FUNCTION Note. The ADLP interrogator link determination function selects the II code of the Mode S interrogator through which a Mode S subnetwork packet may be routed to the desired destination ground DTE II code-dte address correlation. The ADLP shall construct and manage a Mode S interrogator-data terminal equipment (DTE) cross-reference table whose entries are Mode S interrogator identifier (II) codes and ground DTE addresses associated with the ground ATN routers or other ground DTEs. Each entry of the II code-dte cross-reference table shall consist of the 4-bit Mode S II code and the 8-bit binary representation of the ground DTE. Note 1. Due to the requirement for non-ambiguous addresses, a DTE address also uniquely identifies a GDLP. Note 2. An ATN router may have more than one ground DTE address Protocol. The following procedures shall be used: (a) when the GDLP initially detects the presence of an aircraft, or detects contact with a currently acquired aircraft through an interrogator with a new II code, the appropriate fields of the DATA LINK CAPABILITY report shall be examined to determine if, and to what level, the aircraft has the capability to participate in a data exchange. After positive determination of data link capability, the GDLP shall uplink one or more Mode S ROUTE packets. This information shall relate the Mode S II code with the ground DTE addresses accessible through that interrogator. The ADLP shall update the II code- DTE cross-reference table and then discard the Mode S ROUTE packet(s); 110

111 (b) a II code-dte cross-reference table entry shall be deleted when commanded by a Mode S ROUTE packet or when the ADLP recognizes that the transponder has not been selectively interrogated by a Mode S interrogator with a given II code for Ts seconds by monitoring the IIS subfield in Mode S surveillance or Comm-A interrogations (Table 5-1); (c) when the GDLP determines that modification is required to the Mode S interrogator assignment, it shall transfer one or more Mode S ROUTE packets to the ADLP. The update information contained in the Mode S ROUTE packet shall be used by the ADLP to modify its cross-reference table. Additions shall be processed before deletions; (d) when the GDLP sends the initial ROUTE packet after acquisition of a Mode S data link-equipped aircraft, the IN bit shall be set to ONE. This value shall cause the ADLP to perform the procedures as specified in Otherwise, the IN bit shall be set to ZERO; (e) when the ADLP is initialized (e.g. after a power-up procedure), the ADLP shall issue a search request by sending a broadcast Comm-B message with broadcast identifier equal to 255 (FF16, as specified in Table 5-23) and the remaining 6 bytes unused. On receipt of a search request, a GDLP shall respond with one or more Mode S ROUTE packets, clear all SVCs associated with the ADLP, as specified in , and discard the search request. This shall cause the ADLP to initialize the II code-dte cross-reference table; and (f) on receipt of an update request (Table 5-23), a GDLP shall respond with one or more Mode S ROUTE packets and discard the update request. This shall cause the ADLP to update the II code-dte cross-reference table. Note. The update request may be used by the ADLP under exceptional circumstances (e.g. changeover to standby unit) to verify the contents of its II codedte cross reference table PROCEDURES FOR DOWNLINKING MODE S PACKETS When the ADLP has a packet to downlink, the following procedures shall apply: (a) CALL REQUEST packet. If the packet to be transferred is a Mode S CALL REQUEST, the ground DTE address field shall be examined and shall be associated with a connected Mode S 111

112 interrogator using the II code-dte cross reference table. The packet shall be downlinked using the multisite-directed protocol. A request to transfer a packet to a DTE address not in the cross-reference table shall result in the action specified in (b) Other SVC packets. For an SVC, a request to send a packet to a ground DTE shall cause the packet to be multisite directed to the last Mode S interrogator used to successfully transfer (uplink or downlink) a packet to that DTE, provided that this Mode S interrogator is currently in the II code-dte crossreference table. Otherwise, an SVC packet shall be downlinked using the multisite-directed protocol to any other Mode S interrogator associated with the specified ground DTE address. Level 5 transponders shall be permitted to use additional interrogators for downlink transfer as indicated in the II code-dte cross-reference table A downlink frame transfer shall be defined to be successful if its Comm-B or ELM close-out is received from the transponder within Tz seconds as specified in Table 5-1. If the attempt is not successful and an SVC packet is to be sent, the II code-dte cross-reference table shall be examined for another entry with the same called ground DTE address and a different Mode S II code. The procedure shall be retried using the multisite-directed protocol with the new Mode S interrogator. If there are no entries for the required called DTE, or all entries result in a failed attempt, a link failure shall be declared SUPPORT FOR THE DTE(S) GDLP connectivity reporting. The GDLP shall notify the ground DTE(s) of the availability of a Mode S data link-equipped aircraft ( join event ). The GDLP shall also inform the ground DTEs when such an aircraft is no longer in contact via that GDLP ( leave event ). The GDLP shall provide for notification (on request) of all Mode S data link equipped aircraft currently in contact with that GDLP. The notifications shall provide the ground ATN router with the subnetwork point of attachment (SNPA) address of the mobile ATN router, with the position of the aircraft and quality of service as optional parameters. The 112

113 SNPA of the mobile ATN router shall be the DTE address formed by the aircraft address and a sub-address of 0 ( ) ADLP connectivity reporting. The ADLP shall notify all aircraft DTEs whenever the last remaining entry for a ground DTE is deleted from the II code-dte cross-reference table ( ). This notification shall include the address of this DTE Communications requirements. The mechanism for communication of changes in subnetwork connectivity shall be a confirmed service, such as the join/leave events that allow notification of the connectivity status ERROR PROCEDURES Link failure. The failure to deliver a packet to the referenced XDLP after an attempt has been made to deliver this packet via all available interrogators shall be declared to be a link level failure. For an SVC, the XDCE shall enter the State p1 and release all resources associated with that channel. This shall include the cancellation in the transponder of any frames associated with this SVC. A Mode S CLEAR REQUEST packet shall be sent to the DCE via the reformatting process and shall be forwarded by the DCE as an ISO 8208 packet to the local DTE as described in On the aircraft side, the channel shall not be returned to the ADCE channel pool, i.e. does not return to the State p1, until Tr seconds after the link failure has been declared (Table 5-1) ACTIVE CHANNEL DETERMINATION Procedure for d1 State. The XDLP shall monitor the activity of all SVCs, not in a READY State (p1). If an SVC is in the (XDCE) FLOW CONTROL READY State (d1) for more than Tx seconds (the active channel timer, Tables 5-1 and 5-13) without sending a Mode S RR, RNR, DATA, or REJECT packet, then: 113

114 (a) if the last packet sent was a Mode S REJECT packet to which a response has not been received, then the XDLP shall resend that packet; (b) otherwise, the XDLP shall send a Mode S RR or RNR packet as appropriate to the peer XDLP Procedure for other States. If an XDCE SVC is in the p2, p3, p6, p7, d2 or d3 State for more than Tx seconds, the link failure procedure of shall be performed Link failure shall be declared if either a failure to deliver, or a failure to receive, keep-alive packets has occurred. In which case the channel shall be cleared. 1.9 The data link capability report The data link capability report shall be as specified in the Civil Aviation (surveillance and collision avoidance system) Regulations System timers The values for timers shall conform to the values given in Tables 5-1 and Tolerance for all timers shall be plus or minus one per cent Resolution for all timers shall be one second System requirements Data integrity. The maximum bit error rates for data presented at the ADLP/transponder interface or the GDLP/interrogator interface measured at the local DTE/XDLP interface (and vice versa) shall not exceed 10-9 for undetected errors and 10-7 for detected errors. Note. The maximum error rate includes all errors resulting from data transfers across the interfaces and from XDLP internal operation TIMING 114

115 ADLP timing. ADLP operations shall not take longer than 0.25 seconds for regular traffic and seconds for interrupt traffic. This interval shall be defined as follows: (a) Transponders with downlink ELM capability. The time that the final bit of a 128-byte data packet is presented to the DCE for downlink transfer to the time that the final bit of the first encapsulating frame is available for delivery to the transponder. (b) Transponders with Comm-B capability. The time that the final bit of a user data field of 24 bytes is presented to the DCE for downlink transfer to the time that the final bit of the last of the four Comm-B segments that forms the frame encapsulating the user data is available for delivery to the transponder. (c) Transponders with uplink ELM capability. The time that the final bit of the last segment of an ELM of 14 Comm-C segments that contains a user data field of 128 bytes is received by the ADLP to the time that the final bit of the corresponding packet is available for delivery to the DTE. (d) Transponders with Comm-A capability. The time that the final bit of the last segment of four linked Comm-A segments that contains a user data field of 25 bytes is received by the ADLP to the time that the final bit of the corresponding packet is available for delivery to the DTE GDLP TIMING The total time delay across the GDLP, exclusive of transmission delay, shall not be greater than seconds Interface rate. The physical interface between the ADLP and the transponder shall have a minimum bit rate of 100 kilobits per second. 115

116 116

117 117

118 118

119 119

120 120

121 121

122 122

123 123

124 THIRD SCHEDULE (Made under Regulation 45(b)) 1. DCE AND XDCE STATE TABLES 1.4 Tanzania Civil Aviation Authority (TCAA) table requirements. The DCE and XDCE shall function as specified in Tables 5-3 to CAA-U Tables 5-15 through 5-22 shall be applied to: (a) ADLP CAA-U transitions when the XDCE or XDLP terms in parenthesis are omitted; and (b) GDLP State transitions when the terms in parenthesis are used and the XDCE or XDLP preceding them are omitted. 1.5 Diagnostic and cause codes. The table entries for certain conditions indicate a diagnostic code that shall be included in the packet generated when entering the State indicated. The term, D =, shall define the diagnostic code. When A = DIAG, the action taken shall be to generate an ISO 8208 DIAGNOSTIC packet and transfer it to the DTE; the diagnostic code indicated shall define the entry in the diagnostic field of the packet. The cause field shall be set as specified in The reset cause field shall be set as specified in ISO Note 1. The tables provided below specify State requirements in the following order: 5-3 DCE special cases 5-4 DTE effect on DCE restart States 5-5 DTE effect on DCE call setup and clearing States 5-6 DTE effect on DCE reset States 5-7 DTE effect on DCE interrupt transfer States 5-8 DTE effect on DCE flow control transfer States 5-9 XDCE effect on DCE restart States 5-10 XDCE effect on DCE call setup and clearing States 5-11 XDCE effect on DCE reset States 5-12 XDCE effect on DCE interrupt transfer States 5-15 GDLP (ADLP) effect on ADCE (GDCE) packet layer ready States 5-16 GDLP (ADLP) effect on ADCE (GDCE) call setup and clearing States 5-17 GDLP (ADLP) effect on ADCE (GDCE) reset States 124

125 5-18 GDLP (ADLP) effect on ADCE (GDCE) interrupt transfer States 5-19 GDLP (ADLP) effect on ADCE (GDCE) flow control transfer States 5-20 DCE effect on ADCE (GDCE) call setup and clearing States 5-21 DCE effect on ADCE (GDCE) reset States 5-22 DCE effect on ADCE (GDCE) interrupt transfer States Note 2. All tables specify both ADLP and GDLP actions. Note 3. Within the Mode S subnetwork, States p6 and d2 are transient States. Note 4. References to notes in the State tables refer to table-specific notes that follow each State table. Note 5. All diagnostic and cause codes are interpreted as decimal numbers. Note 6. An SVC between an ADCE and a GDCE may be identified by a temporary and/or permanent channel number, as defined in

126 126

127 127

128 128

129 129

130 130

131 131

132 132

133 133

134 134

135 135

136 136

137 137

138 138

139 139

140 140

141 141

142 1. MODE S PACKET FORMATS FOURTH SCHEDULE (Made under regulation 45(c)) 1.1. Formats. The Mode S packet formats shall be as specified in Figures 5-3 to 5-22 as contained in the third schedule Significance of control fields. The structure of the format control fields used in Mode S packets shall be as specified in Figure The significance of all control fields used in these packet formats shall be as follows: 142

143 143

144 144

145 145

146 146

147 147

148 148

149 149

150 150

151 151

152 152

153 FIFTH SCHEDULE (Made under regulation 49) VHF AIR GROUND DIGITAK LINK (VDL) 1. SYSTEM CHARACTERISTICS OF THE GROUND INSTALLATION FOR VHF AIR-GROUND DIGITAL LINK 1.1 Ground station transmitting function Frequency stability. The radio frequency of VDL ground station equipment operation shall not vary more than plus or minus per cent (2 parts per million) from the assigned frequency. 1.2 Power Note. The frequency stability for VDL ground stations using DSB- AM modulation is specified in Part II, Chapter 2 for 25 khz channel spacing. The effective radiated power shall be such as to provide a field strength of at least 75 microvolts per metre (minus 109 dbw/m2) within the defined operational coverage of the facility, on the basis of free-space propagation. 1.3 Spurious emissions Spurious emissions shall be kept at the lowest value which the State of the technique and the nature of the service permit. Note. Appendix S3 to the Radio Regulations specifies the levels of spurious emissions to which transmitters must conform. 1.4 Adjacent channel emissions The amount of power from a VDL ground transmitter under all operating conditions when measured over the 25 khz channel bandwidth of the first adjacent channel shall not exceed 0 dbm. 153

154 After 1 January 2002, the amount of power from all new installations of a VDL ground transmitter under all operating conditions when measured over the 25 khz channel bandwidth of the first adjacent channel shall not exceed 2 dbm The amount of power from a VDL ground transmitter under all operating conditions when measured over the 25 khz channel bandwidth of the second adjacent channel shall be less than minus 25 dbm and from thereon it shall monotonically decrease at the minimum rate of 5 db per octave to a maximum value of minus 52 dbm After 1 January 2002, the amount of power from all new installations of a VDL ground transmitter under all operating conditions when measured over the 25 khz channel bandwidth of the second adjacent channel shall be less than minus 28 dbm After 1 January 2002, the amount of power from all new installations of a VDL ground transmitter under all operating conditions when measured over the 25 khz channel bandwidth of the fourth adjacent channel shall be less than minus 38 dbm, and from thereon it shall monotonically decrease at the minimum rate of 5 db per octave to a maximum value of minus 53 dbm The amount of power from a VDL ground transmitter under all operating conditions when measured over a 16 khz channel bandwidth centred on the first adjacent channel shall not exceed minus 20 dbm After 1 January 2002, the amount of power from all new installations of a VDL ground transmitter under all operating conditions when measured over a 16 khz channel bandwidth centred on the first adjacent channel shall not exceed minus 18 dbm After 1 January 2005, all VDL ground transmitters shall meet the provisions of , , and , subject to the conditions of Requirements of mandatory compliance of the provisions of shall be made on the basis of regional air navigation agreements which specify the airspace of operation and the implementation timescales. The agreements shall provide at least two years notice of mandatory compliance of ground systems. 154

155 SIXTH SCHEDULE (Made under regulation 49) VHF AIR GROUND DIGITAK LINK (VDL) 1. SYSTEM CHARACTERISTICS OF THE AIRCRAFT INSTALLATION FOR VHF AIR-GROUND DIGITAL LINK 1.1 Frequency stability. The radio frequency of VDL aircraft equipment shall not vary more than plus or minus per cent (5 parts per million) from the assigned frequency. 1.2 Power. The effective radiated power shall be such as to provide a field strength of at least 20 microvolts per metre (minus 120 dbw/m2) on the basis of free-space propagation, at ranges and altitudes appropriate to the operational conditions pertaining to the areas over which the aircraft is operated. 1.3 Spurious emissions Spurious emissions shall be kept at the lowest value which the State of the technique and the nature of the service permit. Note. Appendix S3 to the Radio Regulations specifies the levels of spurious emissions to which transmitters must conform. 1.4 Adjacent channel emissions The amount of power from a VDL aircraft transmitter under all operating conditions when measured over the 25 khz channel bandwidth of the first adjacent channel shall not exceed 0 dbm After 1 January 2002, the amount of power from all new installations of a VDL aircraft transmitter under all operating conditions when measured over the 25 khz channel bandwidth of the first adjacent channel shall not exceed 2 dbm. 155

156 1.4.2 The amount of power from a VDL aircraft transmitter under all operating conditions when measured over the 25 khz channel bandwidth of the second adjacent channel shall be less than minus 25 dbm and from thereon it shall monotonically decrease at the minimum rate of 5 db per octave to a maximum value of minus 52 dbm After 1 January 2002, the amount of power from all new installations of a VDL aircraft transmitter under all operating conditions when measured over the 25 khz channel bandwidth of the second adjacent channel shall be less than minus 28 dbm After 1 January 2002, the amount of power from all new installations of a VDL aircraft transmitter under all operating conditions when measured over the 25 khz channel bandwidth of the fourth adjacent channel shall be less than minus 38 dbm, and from thereon it shall monotonically decrease at the minimum rate of 5 db per octave to a maximum value of minus 53 dbm The amount of power from a VDL aircraft transmitter under all operating conditions when measured over a 16 khz channel bandwidth centred on the first adjacent channel shall not exceed minus 20 dbm After 1 January 2002, the amount of power from all new installations of a VDL aircraft transmitter under all operating conditions when measured over a 16 khz channel bandwidth centred on the first adjacent channel shall not exceed minus 18 dbm After 1 January 2005, all VDL aircraft transmitters shall meet the provisions of , , and , subject to the conditions of Requirements of mandatory compliance of the provisions of shall be made on the basis of regional air navigation agreements which specify the airspace of operation and the implementation timescales. The agreements shall provide at least two years notice of mandatory compliance of aircraft systems. 1.5 Receiving function 156

157 1.5.1 Specified error rate. The specified error rate for Mode 2 operation shall be the maximum corrected Bit Error Rate (BER) of 1 in 104. The specified error rate for Mode 3 operation shall be the maximum uncorrected BER of 1 in 103. The specified error rate for Mode 4 operation shall be the maximum uncorrected BER of 1 in 104. Note. The above physical layer BER requirements are derived from the BER requirement imposed by ATN at the subnetwork interface Sensitivity. The receiving function shall satisfy the specified error rate with a desired signal strength of not more than 20 microvolts per metre (minus 120 dbw/m2). Note. The required signal strength at the edge of the service volume takes into account the requirements of the system and signal losses within the system, and considers environmental noise sources Out-of-band immunity performance. The receiving function shall satisfy the specified error rate with a desired signal field strength of not more than 40 microvolts per metre (minus 114 dbw/m2) and with an undesired DSB-AM D8PSK or GFSK signal on the adjacent or any other assignable channel being at least 40 db higher than the desired signal After 1 January 2002, the receiving function of all new installations of VDL shall satisfy the specified error rate with a desired signal field strength of not more than 40 microvolts per metre (minus 114 dbw/m2) and with an undesired VHF DSB-AM, D8PSK or GFSK signal at least 60 db higher than the desired signal on any assignable channel 100 khz or more away from the assigned channel of the desired signal. Note.-This level of interference immunity performance provides a receiver performance consistent with the influence of the VDL RF spectrum mask as specified in with an effective isolation transmitter/receiver isolation of 69 db. Better transmitter and receiver performance could result in less isolation required. Guidance material on the measurement technique is included in the ICAO Handbook on Radio Frequency Spectrum Requirements for 157

158 Civil Aviation including statement of Approved ICAO Policies (Doc 9718) After 1 January 2005, the receiving function of all installations of VDL shall meet the provisions of , subject to the conditions of Requirements of mandatory compliance of the provisions of shall be made on the basis of regional air navigation agreements which specify the airspace of operation and the implementation timescales. The agreement shall provide for at least two years notice of mandatory compliance of aircraft systems INTERFERENCE IMMUNITY PERFORMANCE The receiving function shall satisfy the specified error rate with a desired field strength of not more than 40 microvolts per metre, and with one or more out-of-band signals, except for VHF FM broadcast signals, having a total level at the receiver input of minus 33 dbm. Note. In areas where adjacent higher band signal interference exceeds this specification, a higher immunity requirement will apply The receiving function shall satisfy the specified error rate with a desired field strength of not more than 40 microvolts per metre, and with one or more VHF FM broadcast signals having a total level at the receiver input of minus 5 dbm. 158

159 SEVENTH SCHEDULE (Made under regulation 50(a)) VHF AIR GROUND DIGITAL LINK SYSTEMS) 1. PHYSICAL LAYER PROTOCOLS AND SERVICES The aircraft and ground stations shall access the physical medium operating in simplex mode. 1.1 Functions The physical layer shall provide the following functions: (a) transmitter and receiver frequency control; (b) digital reception by the receiver; (c) digital transmission by the transmitter; and (d) notification services Transmitter/receiver frequency control. The VDL physical layer shall set the transmitter or receiver frequency as commanded by the link management entity (LME). Note. The LME is a link layer entity as contained in the Manuals on VDL Mode 2 and VDL Mode 3 Technical Specifications Digital reception by the receiver. The receiver shall decode input signals and forward them to the higher layers for processing Digital transmission. The VDL physical layer shall appropriately encode and transmit information received from higher layers over the RF channel. 1.2 Modes 2 and 3 common physical layer Modulation scheme. Modes 2 and 3 shall use differentially encoded 8 phase shift keying (D8PSK), using a raised cosine filter with α = 0.6 (nominal value). The information to be transmitted shall be differentially encoded with 3 bits per symbol (baud) transmitted as changes in phase rather than absolute phase. The data stream to be transmitted shall be 159

160 divided into groups of 3 consecutive data bits, least significant bit first. Zeros shall be padded to the end of the transmissions if needed for the final channel symbol Data encoding. A binary data stream entering a differential data encoder shall be converted into three separate binary streams X, Y, and Z so that bits 3n form X, bits 3n + 1 form Y, and bits 3n + 2 form Z. The triplet at time k (Xk, Yk, Zk) shall be converted to a change in phase as shown in Table 6-1*, and the absolute phase φk is the accumulated series of Δφk, that is: φk = φk-1 + Δφk Transmitted signal form. The phase-modulated baseband signal as defined in shall excite the pulse shape filter. 160

161 where: h is the complex impulse response of the pulse shape filter; k is defined in ; φ is defined by the equation in ; t is time; Ts is time duration of each symbol. The output (function of time) of the pulse shape filter (s(t)) shall modulate the carrier frequency. The pulse shape filter shall have a nominal complex frequency response of a raised-cosine filter with α =0.6. * All tables are located at the end of this chapter Modulation rate. The symbol rate shall be symbols/second, resulting in a nominal bit rate of bits/s. The modulation stability requirements for Modes 2 and 3 are provided in Table Mode 2 specific physical layer Note. The Mode 2 specific physical layer specification includes a description of the Mode 2 training sequence, forward error correction (FEC), interleaving, bit scrambling, channel sensing, and physical layer system parameters To transmit a sequence of frames, a station shall insert the bit numbers and flags (per the data link service description for Mode 2 as contained in the Manual on VDL Mode 2 Technical Specifications), compute the 161

162 FEC and the training sequence carry out bit scrambling and finally encode and modulate the RF signal Training sequence. Data transmission shall begin with a demodulator training sequence consisting of five segments: (a) transmitter ramp-up and power stabilization; (b) synchronization and ambiguity resolution; (c) reserved symbol; (d) transmission length; and (e) header FEC. Note. Immediately after these segments follows an AVLC frame with the format as contained in the data link service description in the Manual on VDL Mode 2 Technical Specifications Transmitter ramp-up and power stabilization. The purpose of the first segment of the training sequence, called the ramp-up, is to provide for transmitter power stabilization and receiver AGC settling, and it shall immediately precede the first symbol of the unique word. The duration of the ramp-up shall be five symbol periods. The time reference point (t), for the following specification is the centre of the first unique word symbol, a point that occurs half a symbol period after the end of the ramp-up. Conversely Stated, the beginning of the ramp-up starts at t = 5.5 symbol periods. The transmitted power shall be less than 40 dbc prior to time t = 5.5 symbol periods. The ramp-up shall provide that at time t = 3.0 symbol periods the transmitted power is 90 per cent of the manufacturer s Stated output power or greater (see Figure 6-1*). Regardless of the method used to implement (or truncate) the raised cosine filter, the output of the transmitter between times t = 3.0 and t = 0.5 will appear as if 000 symbols were transmitted during the ramp-up period. 162

163 Note. 1. For Mode 3, the timing reference point is the same as the power reference point. Note 2. It is desirable to maximize the time allowed for the AGC settling time. Efforts shall be made to have power above 90 per cent of nominal output power at t 3.5 symbol periods Synchronization and ambiguity resolution. The second segment of the training sequence shall consist of the unique word: and shall be transmitted from left to right. All figures are located at the end of this chapter Reserved symbol. The third segment of the training sequence shall consist of the single symbol representing 000. Note. This field is reserved for future definition Transmission length. To allow the receiver to determine the length of the final Reed-Solomon block, the transmitter shall send a 17-bit word, from least significant bit (lsb) to most significant bit (msb), indicating the total number of data bits that follow the header FEC 163

164 Note. The length does not include those bits transmitted for: the Reed Solomon FEC, extra bits padded to ensure that the interleaver generates an integral number of 8-bit words, or the extra bits padded to ensure that the data encoder generates an integral number of 3-bit symbols Header FEC. To correct bit errors in the header, a (25, 20) block code shall be computed over the reserved symbol and the transmission length segments. The block code shall be transmitted as the fifth segment. The encoder shall accept the header in the bit sequence that is being transmitted. The five parity bits to be transmitted shall be generated using the following equation: where: P is the parity symbol (P1 shall be transmitted first); R is the reserved symbol; TL is the transmission Length symbol; T is the matrix transpose function; and H is the parity matrix defined below: Bit transmission order. The five parity bits of the resultant vector product shall be transmitted from the left bit first Forward error correction. In order to improve the effective channel throughput by reducing the number of required retransmissions, FEC shall be applied after the training sequence, regardless of frame boundaries FEC calculation. The FEC coding shall be accomplished by means of a systematic fixed-length Reed- Solomon 164

165 Note 1. This code is capable of correcting up to three octets for data blocks of 249 octets (1992 bits). Longer transmissions must be divided up into 1992 bit transmissions and shorter transmissions must be extended by virtual fill with trailing zeros. Six RS-check octets are appended for a total block of 255 octets. The field defining the primitive polynomial of the code shall be as follows: The generator polynomial shall be as follows: where: α is a primitive element of GF(256); GF(256) is a Galois field (GF) of size 256. Note 2. The Reed-Solomon codes are described in the recommendation for Space Data System Standards Telemetry Channel Coding, by the Consultative Committee for Space Data Systems Block lengths. The six RS-check octets shall be calculated on blocks of 249 octets. Longer transmissions shall be split into blocks of 249 octets, per Blocks of shorter length shall be extended to 249 octets by a virtual fill of trailing zeros. The virtual fill shall not be transmitted. Blocks shall be coded according to through No error correction. For blocks with 2 or fewer non-fill octets, no error correction shall be used Single-byte error correction. For blocks with 3 to 30 non-fill octets, all six RS-check octets shall be generated, but only the first two shall be transmitted. The last four RS-check octets shall be treated as erasures at the decoder. 165

166 Two-byte error correction. For blocks with 31 to 67 non-fill octets, all six RS-check octets shall be generated, but only the first four shall be transmitted. The last two RS-check octets shall be treated as erasures at the decoder Three-byte error correction. For blocks with 68 or more non-fill octets, all six RS-check octets shall be generated and transmitted Interleaving. To improve the performance of the FEC, an octet-based table-driven interleaver shall be used. The interleaver shall create a table having 255 octets per row and c rows, where where: (a) the transmission length is as defined in ; and (b) c = the smallest integer greater than or equal to the value of the fraction. After extending the data to an even multiple of 1992 bits, the interleaver shall write the transmission stream into the first 249 octets of each row by taking each consecutive group of eight bits and storing them from the first column to the 249th. The first bit in each group of eight bits shall be stored in the eighth bit position; the first group of 1992 bits shall be stored in the first row, the second group of 1992 bits in the second row, etc. After the FEC is computed on each row, the FEC data (or erasures) shall be stored in columns 250 through 255. The interleaver shall then pass the data to the scrambler by reading out column by column, skipping any octet which contains erasures or all fill bits. All of the bits in an octet shall be transmitted from bit 8 to bit 1. On reception, the de-interleaver shall calculate the number of rows and size of the last (potentially partial) row from the length field in the header. It shall only pass valid data bytes to the higher layer Bit scrambling. To aid clock recovery and to stabilize the shape of the transmitted spectrum, bit scrambling shall be applied. The pseudo noise 166

167 (PN) sequence shall be a 15-stage generator (see Figure 6-2) with the characteristic polynomial: The PN-sequence shall start after the frame synchronization pattern with the initial value with the leftmost bit in the first stage of the register as per Figure 6-2. After processing each bit, the register shall be shifted one bit to the right. For possible encryption in the future this initial value shall be programmed. The sequence shall be added (modulo 2) to the data at the transmit side (scrambling) and to the scrambled data at the receive side (descrambling) per Table 6-3. Note. The concept of a PN scrambler is explained in ITU-R S.446-4, Annex I, Section 4.3.1, Method 1 167

168 1.3.2 MODE 2 CHANNEL SENSING Channel busy to idle detection. When a station receives on-channel power of at least 87 dbm for at least 5 milliseconds, then: (a) with a likelihood of 0.9, it shall continue to consider the channel occupied if the signal level is attenuated to below -92 dbm for less than 1 millisecond; and (b) with a likelihood of 0.9, it shall consider the channel unoccupied if the signal level is attenuated to below 92 dbm for at least 1.5 milliseconds. Note.-The maximum link throughput available to all users is highly sensitive to the RF channel sense delay (from the time when the channel actually changes State until a station detects and acts on that change) and RF channel seizure delay (from the time when a station decides to transmit until the transmitter is sufficiently ramped up to lock out other stations). Accordingly, it is imperative that all efforts are made to reduce those times as the State-of-the-art advances Channel idle to busy detection. With a likelihood of at least 0.9, a station shall consider the channel occupied within 1 millisecond after onchannel power rises to at least 90 dbm The detection of an occupied channel shall occur within 0.5 milliseconds. Note. A higher probability of false alarm is acceptable on the idle to busy detection than the busy to idle detection because of the effects of the two different errors MODE 2 RECEIVER/TRANSMITTER INTERACTION Receiver to transmitter turnaround time. A station shall transmit the training sequence such that the centre of the first symbol of the unique word will be transmitted within 1.25 milliseconds after the result of an access attempt is successful (see Figure 6-3). The total frequency change during the transmission of the unique word shall be less than 10 Hz. After transmission of the unique word, the phase acceleration shall be less than 500 Hz per second. 168

169 Transmitter to receiver turnaround time. The transmitter power shall be 20 dbc within 2.5 symbol periods of the middle of the final symbol of the burst. The transmitter power leakage when the transmitter is in the off State shall be less than 83 dbm. A station shall be capable of receiving and demodulating with nominal performance, an incoming signal within 1.5 milliseconds after transmission of the final information symbol. Note. Reference DO-160D section 21, category H for antenna radiated signals MODE 2 PHYSICAL LAYER SYSTEM PARAMETERS The physical layer shall implement the system parameters as defined in Table

170 Parameter P1 (minimum transmission length). Parameter P1 defines the minimum transmission length that a receiver shall be capable of demodulating without degradation of BER. 1.4 Mode 3 specific physical layer Note. The Mode 3 specific physical layer specification includes a description of Mode 3 management (M) burst and handoff check message (H) burst uplink, M burst downlink, voice/data (V/D) burst, and bit scrambling Management (M) burst and handoff check message (H) burst uplink. The M uplink burst (as contained in the Manual on VDL Mode 3 Technical Specifications) shall consist of three segments, the training sequence followed by the system data and the transmitter ramp down. The H uplink burst (as contained in the Manual on VDL Mode 3 Technical Specifications) shall consist of three segments, the training sequence followed by the handoff check message and the transmitter ramp down Training sequence. Uplink M burst and H burst training sequences shall consist of two components as follows: (a) transmitter ramp up and power stabilization; and (b) synchronization and ambiguity resolution Transmitter ramp-up and power stabilization. This shall be as defined in Section Synchronization and ambiguity resolution. The second component of the training sequence shall consist of the synchronization sequence, known as S2*, as follows:

171 and shall be transmitted from left to right. Note.- The sequence S2* is very closely related to the sequence S2 (Section ). The 15 phase changes between the 16 symbols of S2* are each exactly 180o out of phase from the 15 phase changes associated with S2. This relationship can be used to simplify the process of simultaneously searching for both sequences System data and handoff check message. The non-3t configuration (as contained in the Manual on VDL Mode 3 Technical Specifications) system data shall consist of 32 transmitted symbols. The 96 transmitted bits shall include 48 bits of information and 48 parity bits, generated as 4 Golay (24, 12) code words. The 3T configuration as contained in the Manual on VDL Mode 3 Technical Specifications shall consist of 128 transmitted symbols. The 384 transmitted bits shall include 192 bits of information and 192 parity bits, generated as 16 Golay (24, 12) code words. The 3T configuration handoff check message shall consist of 40 transmitted symbols. The 120 transmitted bits shall include 60 bits of information and 60 parity bits, generated as 5 Golay (24,12) code words. The specific definition of the Golay encoder shall be as follows: If the 12 bit input bit sequence is written as a row vector x, then the 24 bit output sequence can be written as the row vector y, where y = x G, and the matrix G shall be given by 171

172 Note. The extended Golay code allows for the correction of any error pattern with 3 or fewer bit errors and the detection of any 4-bit error pattern Transmitter ramp-down. The transmitter power shall be 20 dbc within 2.5 symbol periods of the middle of the final symbol of the burst. The transmitter power leakage when the transmitter is in the off State shall be less than -83 dbm. Note. Reference RTCA/DO-160D section 21, category H for antenna radiated signals Management (M) burst downlink. The M downlink burst (as contained in the Manual on VDL Mode 3 Technical Specifications) shall consist of three segments, the training sequence followed by the system data and the transmitter ramp down Training sequence. The M downlink burst training sequence shall consist of two components as follows: (a) transmitter ramp up and power stabilization; and (b) synchronization and ambiguity resolution Transmitter ramp-up and power stabilization. This shall be as defined in Synchronization and ambiguity resolution. Three separate synchronization sequences shall be used for this burst type. The standard sequence, known as S1, shall be as follows: and shall be transmitted from left to right. The special sequence used to identify poll responses shall be as defined in The special sequence used to identify net entry requests (S1*) shall use the following sequence: and shall be transmitted from left to right. 172

173 Note. The sequence S1* is very closely related to the sequence S1. The 15 phase changes between the 16 symbols of S1* are each exactly 180o out of phase from the 15 phase changes associated with S1. This relationship can be used to simplify the process of simultaneously searching for both sequences System data. The system data segment shall consist of 16 transmitted symbols. The 48 transmitted bits shall be encoded as 24 bits of system data and 24 bits of parity bits generated as two consecutive (24, 12) Golay code words. The encoding of the (24, 12) Golay code words shouldl be as defined in Transmitter ramp-down. This shall be as defined in Voice or data (V/D) burst. The V/D burst (as contained in the Manual on VDL Mode 3 Technical Specifications) shall consist of four segments: the training sequence followed by the header, the user information segment and the transmitter ramp down. The same V/D burst format shall be used for both uplink and downlink Training sequence. V/D burst training sequence shall consist of two components as follows: (a) transmitter ramp-up and power stabilization; and (b) synchronization and ambiguity resolution Transmitter ramp-up and power stabilization. This shall be as specified in Synchronization and ambiguity resolution. The second component of the training sequence shall consist of the synchronization sequence, known as S2, as follows: and shall be transmitted from left to right Header. The header segment shall consist of 8 transmitted symbols. The 24 transmitted bits shall be encoded as 12 bits of header information and 12 parity bits, generated as a single (24, 12) Golay code word. The encoding of the (24, 12) Golay code word shall be as defined in

174 User information. The user information segment shall consist of bit symbols. When transmitting voice, FEC shall be applied to the analysis output of the vocoder specified in 6.8. The vocoder shall provide satisfactory performance in a BER environment of 10 3 (with a design goal of 10 2). The overall bit rate of the vocoder including FEC is bits/s (except when in the truncated mode in which the bit rate is bits/s) When transmitting user data, the 576 bits shall be encoded as a single Reed-Solomon (72, 62) 28 ary code word. For user data input to the Reed-Solomon encoder of length less than 496 bits, input data shall be padded with zeroes at the end to a full length of 496 bits. The field defining the primitive polynomial of the code shall be as described in The generator polynomial shall be as follows: Note. The Reed-Solomon (72, 62) code is capable of correcting up to five 28-ary (code word) symbol errors in the received word Transmitter ramp-down. This shall be as defined in Interleaving. There shall be no interleaving in Mode 3 operation Bit scrambling. Under Mode 3 operation, bit scrambling, as specified in shall be performed on each burst, starting after the training sequence. The scrambling sequence shall be reinitialized on each burst effectively providing a constant overlay for each of the Mode 3 fixed length bursts Receiver/transmitter interaction. The switching times in this subsection will be defined as the time between the middle of the last information 174

175 symbol of one burst and the middle of the first symbol of the synchronization sequence of the subsequent burst. Note. This nominal time will be shortened by considerations such as the finite width of each symbol due to Nyquist filtering and the ramp up and power stabilization sequence. Such alternative definitions could yield switching times up to 8 symbol periods shorter Receiver to transmitter switching time. An aircraft radio shall be capable of switching from reception to transmission within 17 symbol periods. This time can be relaxed to 33 symbol periods for aircraft radios which do not functions requiring discrete addressing. Note 1. The shortest R/T switching time for an aircraft radio occurs when the reception of an uplink M channel beacon is followed by a V/D transmission in the same slot. In certain instances where aircraft radios do not implement functions requiring discrete addressing, the R/T switching time can be increased since the last two Golay words of the uplink M channel beacon need not be read. Note 2. The minimum turnaround time assumes that in configurations 3V1D, 2V1D, and 3T (as contained in Section of the Manual on VDL Mode 3 Technical Specifications), the aircraft radios will be provided with software that will prevent them from transmitting a downlink M channel message in a slot following the reception of a voice message from another aircraft with a long time delay Transmitter to receiver switching time. An aircraft radio shall be capable of switching from transmission to reception within 32 symbol periods. Note. The worst case T/R switching time for an aircraft radio occurs when it transmits a downlink M channel message and receives a V/D message in the same slot Fringe coverage indication Indication of near edge-of-coverage shall be provided to the VDL Mode 3 aircraft. 175

176 EIGHTH SCHEDULE (Made under regulation 56) VHF AIR GROUND DIGITAL LINK SYSTEMS 1. LINK LAYER PROTOCOLS AND SERVICES 1.1 General information Functionality. The VDL link layer shall provide the following sub layer functions: SERVICE (a) media access control (MAC) sub layer, which requires the use of the carrier sense multiple access (CSMA) algorithm for Mode 2 or TDMA for Mode 3; (b) a data link service (DLS) sub layer: 1) for Mode 2, the DLS sub layer provides connectionoriented point-to-point links using data link entities (DLE) and connectionless broadcast link over the MAC sub layer; and 2) for Mode 3, the DLS sub layer provides acknowledged connectionless point-to-point and point-to-multipoint links over a MAC sub layer that guarantees sequencing; and (c) a VDL management entity (VME), which establishes and maintains DLEs between the aircraft and the ground-based systems using link management entities (LME) Connection-oriented. The VDL Mode 2 link layer shall provide a reliable point-to-point service using a connection-oriented DLS sub layer Connectionless. The VDL Mode 2 and 3 link layers shall provide an unacknowledged broadcast service using a connectionless DLS sub layer. 176

177 Acknowledged connectionless. The VDL Mode 3 link layer shall provide an acknowledged point-to-point service using a connectionless DLS sub layer that relies upon the MAC sub layer to guarantee sequencing MAC sub layer The MAC sub layer shall provide for the transparent acquisition of the shared communications path. It makes invisible to the DLS sublayer the way in which supporting communications resources are utilized to achieve this. Note. Specific MAC services and procedures for VDL Modes 2 and 3 are contained in the Manuals on VDL Mode 2 and VDL Mode 3 Technical Specifications. 1.3 Data link service sublayer For Mode 2, the DLS shall support bit-oriented simplex air-ground communications using the aviation VHF link control (AVLC) protocol. Note. Specific data link services, parameters and protocol definitions for VDL Mode 2 are contained in the Manual on VDL Mode 2 Technical Specifications For Mode 3, the DLS shall support bit-oriented, priority based, simplex air-ground communications using the acknowledged connectionless data link (A-CLDL) protocol. Note. Specific data link services, parameters and protocol definitions for VDL Mode 3 are contained in the Manual on VDL Mode 3 Technical Specifications VDL management entity Services. The VME shall provide link establishment, maintenance and disconnection services as well as support parameter modification. Specific VME services, parameter formats and procedures for Modes 2 and 3 are contained in the Manuals on VDL Mode 2 and Mode 3 Technical Specifications. NINTH SCHEDULE 177

178 (Made under regulation 51(b)) VHF AIR GROUND DIGITAL LINK SYSTEMS 1. SUBNETWORK LAYER PROTOCOLS AND SERVICES 1.1 Architecture for Mode The sub network layer protocol used across the VHF air-ground sub network for VDL Mode 2 is referred to formally as a sub network access protocol (SNAcP) and shall conform to ISO 8208, except as contained in the Manual on VDL Mode 2 Technical Specifications. The SNAcP is contained within the Manual on VDL Mode 2 Technical Specifications as the sub network protocol. If there are any differences between the Manual on VDL Mode 2 Technical Specifications and the cited specifications, the Manual on VDL Mode 2 Technical Specifications shall have precedence. On the air-ground interface, the aircraft sub network entity shall act as a DTE and the ground sub network entity shall act as a DCE. Note. Specific sub network layer protocol access points, services, packet formats, parameters and procedures for VDL Mode 2 are contained in the Manual on VDL Mode 2 Technical Specifications. 1.2 Architecture for Mode The sub network layer used across the VHF air-ground sub network for VDL Mode 3 provides the flexibility to simultaneously support multiple sub network protocols. The currently defined options are to support ISO 8473 connectionless network protocol and to support ISO 8208, both as contained in the Manual on VDL Mode 3 Technical Specifications. The Manual on VDL Mode 3 Technical Specifications shall have precedence with respect to any differences with the cited specifications. For the ISO 8208 interface, both the air and ground sub network entities shall act as DCEs. Note. Specific sub network layer protocol access points, services, packet formats, parameters and procedures for VDL Mode 3 are contained in the Manual on VDL Mode 3 Technical Specifications. 178

179 TENTH SCHEDULE (Made under regulation 50(b)) VDL MODE 4 1. Physical layer protocols and services Note. Unless otherwise Stated, the requirements defined in this section apply to both mobile and ground stations. 1.1 FUNCTIONS TRANSMITTED POWER Airborne installation. The effective radiated power shall be such as to provide a field strength of at least 35 microvolts per metre (minus dbw/m2) on the basis of free space propagation, at ranges and altitudes appropriate to the conditions pertaining to the areas over which the aircraft is operated Ground installation. The effective radiated power shall be such as to provide a field strength of at least 75 microvolts per metre (minus 109 dbw/m2) within the defined operational coverage of the facility, on the basis of free-space propagation TRANSMITTER AND RECEIVER FREQUENCY CONTROL The VDL Mode 4 physical layer shall set the transmitter or receiver frequency as commanded by the link management entity (LME). Channel selection time shall be less than 13 ms after the receipt of a command from a VSS user DATA RECEPTION BY RECEIVER 179

180 The receiver shall decode input signals and forward them to the higher layers for processing DATA TRANSMISSION BY TRANSMITTER Data encoding and transmission. The physical layer shall encode the data received from the data link layer and transmit it over the RF channel. RF transmission shall take place only when permitted by the MAC Order of transmission. The transmission shall consist of the following stages in the following order: (a) transmitter power stabilization; (b) bit synchronization; (c) ambiguity resolution and data transmission; and (d) transmitter decay. Note. The definitions of the stages are given in Sections to Automatic transmitter shutdown. A VDL Mode 4 station shall automatically shut-down power to any final stage amplifier in the event that output power from that amplifier exceeds 30 dbm for more than 1 second. Reset to an operational mode for the affected amplifier shall require a manual operation. Note. This is intended to protect the shared channel resource against so-called stuck transmitters NOTIFICATION SERVICES Signal quality. The operational parameters of the equipment shall be monitored at the physical layer. Signal quality analysis shall be performed in the demodulator process and in the receive process. 180

181 Note. Processes that may be evaluated in the demodulator include bit error rate (BER), signal to noise ratio (SNR), and timing jitter. Processes that may be evaluated in the receiver include received signal level and group delay Arrival time. The arrival time of each received transmission shall be measured with a two-sigma error of 5 microseconds The receiver shall be capable of measuring the arrival time within a two-sigma error of 1 microsecond. 1.2 PROTOCOL DEFINITION FOR GFSK Modulation scheme. The modulation scheme shall be GFSK. The first bit transmitted (in the training sequence) shall be a high tone and the transmitted tone shall be toggled before transmitting a 0 (i.e. non-return to zero inverted encoding) Modulation rate. Binary ones and binary zeros shall be generated with a modulation index of 0.25 ± 0.03 and a BT product of 0.28 ± 0.03, producing data transmission at a bit rate of bits/s ± 50 ppm STAGES OF TRANSMISSION Transmitter power stabilization. The first segment of the training sequence is the transmitter power stabilization, which shall have a duration of 16 symbol periods. The transmitter power level shall be no less than 90 per cent of the steady State power level at the end of the transmitter power stabilization segment Bit synchronization. The second segment of the training sequence shall be the 24-bit binary sequence , transmitted from left to right immediately before the start of the data segment Ambiguity resolution and data transmission. The transmission of the first bit of data shall start 40 bit intervals 181

182 (approximately microseconds) ± 1 microsecond after the nominal start of transmission. Note 1. This is referenced to emissions at the output of the antenna. Note 2. Ambiguity resolution is performed by the link layer Transmitter decay. The transmitted power level shall decay at least by 20 db within 300 microseconds after completing a transmission. The transmitter power level shall be less than -90 dbm within 832 microseconds after completing a transmission. 1.3 CHANNEL SENSING Estimation of noise floor. A VDL Mode 4 station shall estimate the noise floor based on power measurements of the channel whenever a valid training sequence has not been detected The algorithm used to estimate the noise floor shall be such that the estimated noise floor shall be lower than the maximum power value measured on the channel over the last minute when the channel is regarded as idle. Note. The VDL Mode 4 receiver uses an energy sensing algorithm as one of the means to determine the State of the channel (idle or busy). One algorithm that can be used to estimate the noise floor is described in the Manual on VDL Mode 4 Technical Specifications Channel idle to busy detection. A VDL Mode 4 station shall employ the following means to determine the channel idle to busy transition at the physical layer Detection of a training sequence. The channel shall be declared busy if a VDL Mode 4 station detects a valid training sequence followed by a frame flag Measurement of channel power. Regardless of the ability of the demodulator to detect a valid training sequence, a VDL Mode 4 station shall consider the channel busy with at least a 182

183 95 per cent probability within 1 ms after onchannel power rises to the equivalent of at least four times the estimated noise floor for at least 0.5 milliseconds CHANNEL BUSY TO IDLE DETECTION A VDL Mode 4 station shall employ the following means to determine the channel busy to idle transition Measurement of transmission length. When the training sequence has been detected, the channel busy State shall be held for a period of time at least equal to 5 milliseconds, and subsequently allowed to transition to the idle State based on measurement of channel power Measurement of channel power. When not otherwise held in the channel busy State, a VDL Mode 4 station shall consider the channel idle with at least a 95 per cent probability if onchannel power falls below the equivalent of twice the estimated noise floor for at least 0.9 milliseconds. 1.4 RECEIVER/TRANSMITTER INTERACTION Receiver to transmitter turnaround time. A VDL Mode 4 station shall be capable of beginning the transmission of the transmitter power stabilization sequence within 16 microseconds after terminating the receiver function Frequency change during transmission. The phase acceleration of the carrier from the start of the synchronization sequence to the data end flag shall be less than 300 Hz per second Transmitter to receiver turnaround time. A VDL Mode 4 station shall be capable of receiving and demodulating with nominal performance an incoming signal within 1 ms after completing a transmission. Note. Nominal performance is defined as a bit error rate (BER) of

184 1.5 PHYSICAL LAYER SYSTEM PARAMETERS PARAMETER P1 (MINIMUM TRANSMISSION LENGTH) A receiver shall be capable of demodulating a transmission of minimum length P1 without degradation of BER The value of P1 shall be bits PARAMETER P2 (NOMINAL CO-CHANNEL INTERFERENCE PERFORMANCE) The parameter P2 shall be the nominal co-channel interference at which a receiver shall be capable of demodulating without degradation in BER The value of P2 shall be 12 db. 1.6 FM BROADCAST INTERFERENCE IMMUNITY PERFORMANCE FOR VDL MODE 4 RECEIVING SYSTEMS A VDL Mode 4 station shall conform to the requirements defined in Fifteenth Schedule when operating in the band MHz A VDL Mode 4 station shall conform to the requirements defined below when operating in the band MHz The VDL Mode 4 receiving system shall meet the requirements specified in Fifteenth Schedule in the presence of twosignal, third-order inter modulation products caused by VHF FM broadcast signals having levels in accordance with the following: for VHF FM sound broadcasting signals in the range MHz 184

185 and for VHF FM sound broadcasting signals below MHz, where the frequencies of the two VHF FM sound broadcasting signals produce, within the receiver, a two-signal, third-order inter-modulation product on the desired VDL Mode 4 frequency. N1 and N2 are the levels (dbm) of the two VHF FM sound broadcasting signals at the VDL Mode 4 receiver input. Neither level shall exceed the desensitization criteria set forth in Δf = f1, where f1 is the frequency of N1, the VHF FM sound broadcasting signal closer to MHz. Note. The FM intermodulation immunity requirements are not applied to a VDL Mode 4 channel operating below MHz, and hence frequencies below MHz are not intended for general assignments The VDL Mode 4 receiving system shall not be desensitized in the presence of VHF FM broadcast signals having levels in accordance with Tables

186 2. Link layer Note. Details on link layer functions are contained in the Manual on VDL Mode 4 Technical Specifications. 3. Subnetwork layer and SNDCF Note. Details on subnetwork layer functions and SNDCF are contained in the Manual on VDL Mode 4 Technical Specifications. 4. ADS-B applications Note. Details on ADS-B application functions are contained in the Manual on VDL Mode 4 Technical Specifications. 186

187 ELEVENTH SCHEDULE (Made under regulation 66) 1. TECHNICAL PROVISIONS RELATING TO INTERNATIONAL GROUND-GROUND DATA INTERCHANGE AT MEDIUM AND HIGHER SIGNALLING RATES Note. Throughout this section in the context of coded character sets, the term unit means the unit of selective information and is essentially equivalent to the term bit. 1.1 General In international data interchange of characters, a 7-unit coded character set providing a repertoire of 128 characters and designated as International Alphabet No. 5 (IA-5) shall be used. Compatibility with the 5-unit coded character set of International Telegraph Alphabet No. 2 (ITA-2) shall be ensured where applicable When the provisions of are applied, International Alphabet No. 5 (IA-5) contained in Table 8-2 shall be used The serial transmission of units comprising an individual character of IA- 5 shall be with the low order unit (b1) transmitted first When IA-5 is used, each character shall include an additional unit for parity in the eighth level position When the provisions of are applied, the sense of the character parity bit shall produce even parity in links which operate on the startstop principle, and odd parity in links using end-to-end synchronous operations Character-for-character conversion shall be as listed in Tables 8-3 and 8-4 for all characters which are authorized in the AFTN format for transmission on the AFS in both IA-5 and ITA

188 Characters which appear in only one code set, or which are not authorized for transmission on the AFS shall be as depicted in the code conversion tables. 1.2 Data transmission characteristics The data signalling rate shall be chosen from among the following: bits/s bits/s bits/s bits/s bits/s The type of transmission for each data signalling rate shall be chosen as follows: Data signalling rate Type of transmission bits/s Synchronous or asynchronous serial transmission bits/s Synchronous or asynchronous serial transmission bits/s Synchronous serial transmission bits/s Synchronous serial transmission bits/s Synchronous serial transmission The type of modulation for each data signalling rate shall be chosen as follows: Data signalling rate Type of modulation bits/s Frequency bits/s Frequency bits/s Phase bits/s Phase bits/s Phase-amplitude Note. This standard does not necessarily apply to ground-ground extensions of air-ground links used exclusively for the transfer of airground data, inasmuch as such circuits may be considered as part of the air-ground link. 188

189 1.2.4 CHARACTER STRUCTURE ON DATA LINKS Character parity shall not be used for error checking on CIDIN links. Parity appended to IA-5 coded characters per , prior to entry to the CIDIN shall be ignored. For messages exiting the CIDIN, parity shall be generated in accordance with Characters of less than eight bits in length shall be padded out to eight bits in length before transmission over any octet-based or bit-oriented communications network. The padding bits shall occupy the higher order end of the octet, i.e. bit 8, bit 7 as required, and shall have the binary values When exchanging data over CIDIN links using bit-oriented procedures, the entry centre address, exit centre addresses and destination addresses in the Transport and CIDIN Packet Headers shall be in the IA-5 character set contained in Table When transmitting messages in AFTN format over CIDIN links using bit-oriented procedures, the messages shall be in the IA-5 character set contained in Table Ground-ground character-oriented data link control procedures Note. The provisions of this section pertain to ground-ground data interchange applications using IA-5 prescribed by and which employ the ten transmission control characters (SOH, STX, ETX, EOT, ENQ, ACK, DLE, NAK, SYN, and ETB) for data link control, over synchronous or asynchronous transmission facilities Descriptions. The following descriptions shall apply to data link applications contained in this section: (a) A master station is that station which has control of the data link at a given instant. (b) A slave station is one that has been selected to receive a transmission from the master station. (c) A control station is the single station on a multipoint link that is permitted to assume master status and deliver messages to one or more individually selected (non-control) tributary stations, or 189

190 it is permitted to assign temporary master status to any of the other tributary stations MESSAGE COMPOSITION (a) A transmission shall consist of characters from IA-5 transmitted in accordance with and shall be either an information message or a supervisory sequence. (b) An information message used for the exchange of data shall take one of the following forms: Note 2. In formats 2), 4), and 5) above which end with ETB, some continuation is required. 190

191 (c) A supervisory sequence shall be composed of either a single transmission control character (EOT, ENQ, ACK or NAK) or a single transmission control (ENQ) preceded by a prefix of up to 15 non-control characters, or the character DLE used in conjunction with other graphic and control characters to provide additional communication control functions Three system categories are specified in terms of their respective circuit characteristics, terminal configurations, and message transfer procedures as follows: System category A: two-way alternate, multipoint allowing either centralized or non-centralized operation and single or multiple messageoriented information transfers without replies (but with delivery verification). System category B: two-way simultaneous, point-to-point employing message associated blocking and modulo 8 numbering of blocks and acknowledgements. System category C: two-way alternate, multipoint allowing only centralized (computer-to-terminal) operation, single or multiple message transfers with replies In addition to the characteristics prescribed in the paragraphs that follow for both system categories A and B, other parameters that shall be accounted for in order to ensure viable, operationally reliable communications include: (a) the number of SYN characters required to establish and maintain synchronization; Note. Normally the transmitting station sends three contiguous SYN characters and the receiving station detects at least two before any action is taken. (b) the values of system time-outs for such functions as idle line and no response as well as the number of automatic retries that are to be attempted before manual intervention is signalled; (c) the composition of prefixes within a 15 character maximum. 191

192 Note. By agreement between the administrations concerned, it is permissible for supervisory signals to contain a station identification prefix using characters selected from columns 4 through 7 of IA For multipoint implementations designed to permit only centralized (computer-toterminal) operations, the provisions of shall be employed BLOCK CHECK CHARACTER Both system category A and B shall utilize a block check character to determine the validity of a transmission The block check character shall be composed of 7 bits plus a parity bit Each of the first 7 bits of the block check character shall be the modulo 2 binary sum of every element in the same bit 1 to bit 7 column of the successive characters of the transmitted block The longitudinal parity of each column of the block, including the block check character, shall be even The sense of the parity bit of the block check character shall be the same as for the information characters (see ) SUMMATION The summation to obtain the block check character shall be started by the first appearance of either SOH (start of heading) or STX (start of text) The starting character shall not be included in the summation If an STX character appears after the summation has been started by SOH, then the STX character shall be included in the summation as if it were a text character With the exception of SYN (synchronous idle), all the characters which are transmitted after the start of the block check summation shall be included in the summation, including the ETB (end of 192

193 transmission/block) or ETX (end of text) control character which signals that the following character is the block check character No character, SYN or otherwise, shall be inserted between the ETB or ETX character and the block check character DESCRIPTION OF SYSTEM CATEGORY A System category A is one in which a number of stations are connected by a multipoint link and one station is permanently designated as the control station which monitors the link at all times to ensure orderly operation LINK ESTABLISHMENT PROCEDURE To establish the link for transmission, the control station shall either: (a) poll one of the tributary stations to assign it master status; or (b) assume master status and select one or more tributary (slave) stations to receive a transmission Polling shall be accomplished by the control station sending a polling supervisory sequence consisting of a prefix identifying a single tributary station and ending in ENQ A tributary station detecting its assigned polling supervisory sequence shall assume master status and respond in one of two ways: (a) if the station has a message to send, it shall initiate a selection supervisory sequence as described in ; (b) if the station has no message to send, it shall send EOT, and master status shall revert to the control station If the control station detects an invalid or no response resulting from a poll, it shall terminate by sending EOT prior to resuming polling or selection Selection shall be accomplished by the designated master station sending a selection supervisory sequence consisting of a prefix identifying a single station and ending in ENQ. 193

194 A station detecting its assigned selection supervisory sequence shall assume slave status and send one of two replies: (a) if the station is ready to receive, it shall send a prefix followed by ACK. Upon detecting this reply, the master station shall either select another station or proceed with message transfer; (b) if the station is not ready to receive, it shall send a prefix followed by NAK and thereby relinquish slave status. If the master station receives NAK, or no reply, it shall either select another or the same tributary station or terminate; (c) it shall be permissible for N retries (N 0) to be made to select a station for which NAK, an invalid reply, or no response has been received If one or more stations have been selected and have properly responded with ACK, the master station shall proceed with message transfer MESSAGE TRANSFER PROCEDURE The master station shall send a message or series of messages, with or without headings to the selected slave station(s) The transmission of a message shall: (d) begin with: 1. SOH if the message has a heading, 2. STX if the message has no heading; (e) be continuous, ending with ETX, immediately followed by a block check character (BCC) After transmitting one or more messages, the master station shall verify successful delivery at each selected slave station DELIVERY VERIFICATION PROCEDURE The master station shall send a delivery verification supervisory sequence consisting of a prefix identifying a single slave station and ending in ENQ A slave station detecting its assigned delivery verification supervisory sequence shall send one of two replies: 194

195 (a) if the slave station properly received all of the transmission, it shall send an optional prefix followed by ACK; (b) if the slave station did not receive all of the transmission properly, it shall send an optional prefix followed by NAK If the master station receives no reply or an invalid reply, it shall request a reply from the same or another slave station until all selected stations have been properly accounted for If the master station receives a negative reply (NAK) or, after N 0 repeat attempts, no reply, it shall repeat that transmission to the appropriate slave stations at a later opportunity After all messages have been sent and delivery verified, the master station shall proceed with link termination LINK TERMINATION PROCEDURE The terminate function, negating the master or slave status of all stations and returning master status to the control station, shall be accomplished by the master station transmitting EOT DESCRIPTION OF SYSTEM CATEGORY B System category B is one in which two stations are on a point-to-point, full-duplex link and each station has the capability to maintain concurrent master and slave status, i.e. master status on its transmit side and slave status on its receive side and both stations can transmit simultaneously LINK ESTABLISHMENT PROCEDURE To establish the link for message transfers (from the calling to the called station), the calling station shall request the identity of the called station by sending an identification supervisory sequence consisting of a DLE character followed by a colon character, an optional prefix, and ENQ The called station, upon detecting ENQ, shall send one of two replies: 195

196 (a) if ready to receive, it shall send a sequence consisting of a DLE followed by a colon, a prefix which includes its identity and ended by ACK0 (see ). This establishes the link for message transfers from the calling to the called station; (b) if not ready to receive, it shall send the above sequence with the ACK0 replaced by NAK Establishment of the link for message transfers in the opposite direction can be initiated at any time following circuit connection in a similar manner to that described above MESSAGE TRANSFER PROCEDURE System category B message transfer provides for message associated blocking with longitudinal checking and modulo 8 numbered acknowledgements It is permissible for a transmission block to be a complete message or a portion of a message. The sending station shall initiate the transmission with SOTB N followed by: (a) SOH if it is the beginning of a message that contains a heading; (b) STX if it is the beginning of a message that has no heading; (c) SOH if it is an intermediate block that continues a heading; (d) STX if it is an intermediate block that continues a text. Note. SOTB N is the two-character transmission control sequence DLE = (characters 1/0, and 3/13) followed by the block number, N, where N is one of the IA-5 characters 0, (characters 3/0, 3/1... 3/7) A block which ends at an intermediate point within a message shall be ended with ETB; a block which ends at the end of a message shall be ended with ETX It shall be permissible for each station to initiate and continue to send messages to the other concurrently according to the following sequence. 196

197 (a) It shall be permissible for the sending station (master side) to send blocks, containing messages or parts of messages, continuously to the receiving station (slave side) without waiting for a reply. (b) It shall be permissible for replies, in the form of slave responses, to be transmitted by the receiving station while the sending station is sending subsequent blocks. Note. By use of modulo 8 numbering of blocks and replies, it shall be permissible for the sending station to send as many as seven blocks ahead of the received replies before being required to stop transmission until six or less blocks are outstanding. (c) If a negative reply is received, the sending station (master side) shall start retransmission with the block following the last block for which the proper affirmative acknowledgement was received Slave responses shall be according to one of the following: (a) if a transmission block is received without error and the station is ready to receive another block, it shall send DLE, a colon, an optional prefix, and the appropriate acknowledgement ACKN (referring to the received block beginning with SOTB N, e.g. ACK0, transmitted as DLE0 is used as the affirmative reply to the block numbered SOTB0, DLE1 for SOTB1, etc.); (b) if a transmission block is not acceptable, the receiving station shall send DLE, a colon, an optional prefix, and NAK Slave responses shall be interleaved between message blocks and transmitted at the earliest possible time LINK TERMINATION PROCEDURE If the link has been established for message transfers in either or both directions, the sending of EOT by a station shall signal the end of message transfers in that direction. To resume message transfers after sending EOT, the link shall be re-established in that direction. 197

198 EOT shall only be transmitted by a station after all outstanding slave responses have been received or otherwise accounted for CIRCUIT DISCONNECTION On switched connections, the data links in both directions shall be terminated before the connection is cleared. In addition, the station initiating clearing of the connection shall first announce its intention to do so by transmitting the two-character sequence DLE EOT, followed by any other signals required to clear the connection DESCRIPTION OF SYSTEM CATEGORY C (CENTRALIZED) System category C (centralized) is one (like system category A) in which a number of stations are connected by a multipoint link and one station is designated as the control station but (unlike system category A) provides only for centralized (computer-to-terminal) operations where message interchange (with replies) shall be constrained to occur only between the control and a selected tributary station LINK ESTABLISHMENT PROCEDURE To establish the link for transmission the control station shall either: (a) poll one of the tributary stations to assign it master status; or (b) assume master status and select a tributary station to assume slave status and receive a transmission according to either of two prescribed selection procedures: 1. selection with response (see ); or 2. fast select (see ) Polling is accomplished by the control station sending a polling supervisory sequence consisting of a prefix identifying a single tributary station and ending in ENQ A tributary station detecting its assigned polling supervisory sequence shall assume master status and respond in one of two ways: (a) if the station has a message to send, it shall initiate message transfer. The control station assumes slave status; 198

199 (b) if the station has no message to send, it shall send EOT and master status shall revert to the control station If the control station detects an invalid or no response resulting from a poll, it shall terminate by sending EOT prior to resuming polling or selection Selection with response is accomplished by the control station assuming master status and sending a selection supervisory sequence consisting of a prefix identifying a single tributary station and ending in ENQ A tributary station detecting its assigned selection supervisory sequence shall assume slave status and send one of two replies: (a) if the station is ready to receive, it shall send an optional prefix followed by ACK. Upon detecting this reply, the master station shall proceed with message transfer; (b) if the station is not ready to receive, it shall send an optional prefix followed by NAK. Upon detecting NAK, it shall be permissible for the master station to again attempt selecting the same tributary station or initiate termination by sending EOT. Note. If the control station receives an invalid or no reply, it is permitted to attempt again to select the same tributary or after N retries (N 0) either to exit to a recovery procedure or to initiate termination by sending EOT Fast select is accomplished by the control station assuming master status and sending a selection supervisory sequence, and without ending this transmission with ENQ or waiting for the selected tributary to respond, proceeding directly to message transfer MESSAGE TRANSFER PROCEDURE The station with master status shall send a single message to the station with slave status and wait for a reply The message transmission shall begin with: 199

200 (a) SOH if the message has a heading, STX if the message has no heading; and (b) be continuous, ending with ETX, immediately followed by BCC The slave station, upon detecting ETX followed by BCC, shall send one of two replies: (a) if the messages were accepted and the slave station is ready to receive another message, it shall send an optional prefix followed by ACK. Upon detecting ACK, the master station shall be permitted either to transmit the next message or initiate termination; (b) if the message was not accepted and the slave station is ready to receive another message, it shall send an optional prefix followed by NAK. Upon detecting NAK, the master station may either transmit another message or initiate termination. Following the NAK reply, the next message transmitted need not be a retransmission of the message that was not accepted If the master station receives an invalid or no reply to a message, it shall be permitted to send a delivery verification supervisory sequence consisting of an optional prefix followed by ENQ. Upon receipt of a delivery verification supervisory sequence, the slave station repeats its last reply N retries (N 0) may be made by the master station in order to get a valid slave reply. If a valid reply is not received after N retries, the master station exits to a recovery procedure LINK TERMINATION PROCEDURE The station with master status shall transmit EOT to indicate that it has no more messages to transmit. EOT shall negate the master/slave status of both stations and return master status to the control station. 1.4 Ground-ground bit-oriented data link control procedures Note. The provisions of this section pertain to ground-ground data interchange applications using bit-oriented data link control procedures enabling transparent, synchronous transmission that is independent of 200

201 any encoding; data link control functions are accomplished by interpreting designated bit positions in the transmission envelope of a frame The following descriptions shall apply to data link applications contained in this section: (a) Bit-oriented data link control procedures enable transparent transmission that is independent of any encoding. (b) A data link is the logical association of two interconnected stations, including the communication control capability of the interconnected stations. (c) A station is a configuration of logical elements, from or to which messages are transmitted on a data link, including those elements which control the message flow on the link via communication control procedures. (d) A combined station sends and receives both commands and responses and is responsible for control of the data link. (e) Data communication control procedures are the means used to control and protect the orderly interchange of information between stations on a data link. (f) A component is defined as a number of bits in a prescribed order within a sequence for the control and supervision of the data link. (g) An octet is a group of 8 consecutive bits. (h) A sequence is one or more components in prescribed order comprising an integral number of octets. (i) A field is a series of a specified number of bits or specified maximum number of bits which performs the functions of data link or communications control or constitutes data to be transferred. (j) A frame is a unit of data to be transferred over the data link, comprising one or more fields in a prescribed order. (k) A common ICAO data interchange network (CIDIN) switching centre is that part of an automatic AFTN switching centre which provides for the entry, relay, and exit centre functions using the bit-oriented link and CIDIN network procedures specified in this section and includes the appropriate interface(s) with other parts of the AFTN and with other networks. 201

202 1.4.2 BIT-ORIENTED DATA LINK CONTROL PROCEDURES FOR POINT-TO-POINT, GROUND-GROUND DATA INTERCHANGE APPLICATIONS EMPLOYING SYNCHRONOUS TRANSMISSION FACILITIES Note. The following link level procedures are the same as the LAPB link level procedures described in ITU CCITT Recommendation X.25, Section 2, Yellow Book (1981 version). Later versions of Recommendation X.25 will be reviewed as they are released to ascertain whether or not they should be adopted Frame format. Frames shall contain not less than 32 bits, excluding the opening and closing flags, and shall conform to the following format: A frame shall consist of an opening flag (F), an address field (A), a control field (C), an optional information field (I), a frame check sequence (FCS), and a closing flag sequence (F), and shall be transmitted in that order. Note. In relation to CIDIN, the opening flag, the fields A and C, the FCS and the closing flag form together the Data Link Control Field (DLCF). The field I is denoted as the Link Data Field (LDF) The flag (F) shall be the 8-bit sequence which delimits the beginning and ending of each frame. It shall be permissible for the closing flag of a frame to also serve as the opening flag of the next frame The address (A) field shall consist of one octet, excluding 0 bits added to achieve transparent transmission, which shall contain the link address of the combined station The control (C) field shall consist of one octet, excluding 0 bits added to achieve transparent transmission, and shall contain the commands, responses, and frame sequence number components for the control of the data link. 202

203 The information (I) field shall contain digital data which may be presented in any code or sequence but shall not exceed a maximum of 259 octets, excluding 0 bits added to achieve transparent transmission. The I field shall always be a multiple of 8 bits in length The frame check sequence (FCS) shall consist of two octets, excluding 0 bits added to achieve transparent transmission, and shall contain the error detecting bits A frame check sequence (FCS) shall be included in each frame for the purpose of error checking The error checking algorithm shall be a cyclic redundancy check (CRC) The CRC polynomial (P(x)) shall be The FCS shall be a 16-bit sequence. This FCS shall be the ones complement of the remainder, R(x), obtained from the modulo 2 division of by the CRC polynomial, P(x). G(x) shall be the contents of the frame existing between, but including neither, the final bit of the opening flag northe first bit of the FCS, excluding bits inserted for transparent transmission. K shall be the length of G(x) (number of bits) The generation and checking of the FCS accumulation shall be as follows: (a) the transmitting station shall initiate the FCS accumulation with the first (least significant) bit of the address (A) field 203

204 and shall include all bits up to and including the last bit preceding the FCS sequence, but shall exclude all 0 bits (if any) inserted to achieve transparent transmission; (b) upon completion of the accumulation the FCS shall be transmitted, starting with bit b1 (highest order coefficient) and proceeding in sequence to bit b16 (lowest order coefficient) as shown below; First bit transmitted (c) the receiving station shall carry out the cyclic redundancy check (CRC) on the content of the frame commencing with the first bit received following the opening flag, and shall include all bits up to and including the last bit preceding the closing flag, but shall exclude all 0 bits (if any) deleted according to the rules for achievement of transparency; (d) upon completion of the FCS accumulation, the receiving station shall examine the remainder. In the absence of transmission error, the remainder shall be Achievement of transparency. The frame format contents (A, C, link data field, and FCS) shall be capable of containing any bit configuration The following rules shall apply to all frame contents, except flag sequences: (a) the transmitting station shall examine the frame contents before transmission, and shall insert a single 0 bit 204

205 immediately following each sequence of 5 consecutive 1 bits; (b) the receiving station shall examine the received frame contents for patterns consisting of 5 consecutive 1 bits immediately followed by one (or more) 0 bit(s) and shall remove the 0 bit which directly follows 5 consecutive 1 bits Special transmission sequences and related link States. In addition to employing the prescribed repertoire of commands and responses to manage the interchange of data and control information, stations shall use the following conventions to signal the indicated conditions: MODES (a) Abort is the procedure by which a station in the process of sending a frame ends the frame in an unusual manner such that the receiving station shall ignore the frame. The conventions for aborting a frame shall be: 1. transmitting at least seven, but less than fifteen, one bits (with no inserted zeros); 2. receiving seven one bits. (b) Active link State. A link is in an active State when a station is transmitting a frame, an abort sequence, or interframe time fill. When the link is in the active State, the right of the transmitting station to continue transmission shall be reserved. (c) Interframe time fill. Interframe time fill shall be accomplished by transmitting continuous flags between frames. There is no provision for time fill within a frame. (d) Idle link State. A link is in an idle State when a continuous one condition is detected that persists for 15 bit times, or longer. Idle link time fill shall be a continuous one condition on the link. (e) Invalid frame. An invalid frame is one that is not properly bounded by two flags or one which is shorter than 32 bits between flags. 205

206 Operational mode. The operational mode shall be the asynchronous balanced mode (ABM) It shall be permissible for a combined station in ABM to transmit without invitation from the associated station A combined station in ABM shall be permitted to transmit any command or response type frame except DM Non-operational mode. The non-operational mode shall be the asynchronous disconnected mode (ADM) in which a combined station is logically disconnected from the data link It shall be permissible for a combined station in ADM to transmit without invitation from the associated station A combined station in ADM shall transmit only SABM, DISC, UA and DM frames. (See for a description of the commands and responses to which these frame types refer.) A combined station in ADM shall transmit a DM when a DISC is received, and shall discard all other received command frames except SABM. If a discarded command frame has the P bit set to 1, the combined station shall transmit a DM with the F bit set to Control field functions and parameters. Control fields contain a command or a response and sequence numbers where applicable. Three types of control fields shall be used to perform: (a) numbered information transfer (I-frames); (b) numbered supervisory functions (S-frames); and (c) unnumbered control functions (U-frames). The control field formats shall be as shown in Table 8-5. The functional frame designation associated with each type control field as well as the control field parameters employed in performing these functions shall be described in the following paragraphs. 206

207 The I-frame type is used to perform information transfers. Except for some special cases it is the only format which shall be permitted to contain an information field The S-frame type is used for supervisory commands and responses that perform link supervisory control functions such as acknowledge information frames, request transmission or retransmission of information frames, and to request a temporary suspension of transmission of I-frames. No information field shall be contained in the S-frame The U-frame type is used for unnumbered commands and responses that provide additional link control functions. One of the U-frame responses, the frame reject (FRMR) response, shall contain an information field; all other frames of the U-frame type shall not contain an information field The station parameters associated with the three control field types shall be as follows: (a) Modulus. Each I-frame shall be sequentially numbered with a send sequence count, N(S), having value 0 through modulus minus one (where modulus is the modulus of the sequence numbers). The modulus shall be 8. The maximum number of sequentially numbered I-frames that a station shall have outstanding (i.e. unacknowledged) at any given time shall never exceed one less than the modulus of the sequence numbers. This restriction on the number of outstanding frames is to prevent any ambiguity in the association of transmission frames with sequence numbers during normal operation and/or error recovery. (b) The send State variable V(S) shall denote the sequence number of the next in-sequence I-frame to be transmitted. 1. The send State variable shall take on the value 0 through modulus minus one (modulus is the modulus of the sequence numbering and the numbers cycle through the entire range). 2. The value of V(S) shall be incremented by one with each successive in-sequence I-frame transmission, but shall not exceed the value of 207

208 N(R) contained in the last received frame by more than the maximum permissible number of outstanding I-frames (k). See i) below for the definition of k. (c) Prior to transmission of an in-sequence I-frame, the value of N(S) shall be updated to equal the value of V(S). (d) The receive State variable V(R) shall denote the sequence number of the next in-sequence I-frame to be received. 1. V(R) shall take on the values 0 through modulus minus one. 2. The value of V(R) shall be incremented by one after the receipt of an error-free, in-sequence I- frame whose send sequence number N(S), equals V(R). (e) All I-frames and S-frames shall contain N(R), the expected sequence number of the next received frame. Prior to transmission of either an I or an S type frame, the value of N(R) shall be updated to equal the current value of the receive State variable. N(R) indicates that the station transmitting the N(R) has correctly received all I-frames numbered up to and including N(R) 1. (f) Each station shall maintain an independent send State variable, V(S), and receive State variable, V(R), on the I- frames it sends and receives. That is, each combined station shall maintain a V(S) count on the I-frames it transmits and a V(R) count on the I-frames it has correctly received from the remote combined station. (g) The poll (P/F) bit shall be used by a combined station to solicit (poll) a response or sequence of responses from the remote combined station. (h) The final (P/F) bit shall be used by the remote combined station to indicate the response frame transmitted as the result of a soliciting (poll) command. (i) The maximum number (k) of sequentially numbered I-frames that a station may have outstanding (i.e. unacknowledged) at any given time is a station parameter which shall never exceed the modulus. 208

209 Note. k is determined by station buffering limitations and should be the subject of bilateral agreement at the time of circuit establishment Commands and responses. It shall be permissible for a combined station to generate either commands or responses. A command shall contain the remote station address while a response shall contain the sending station address. The mnemonics associated with all of the commands and responses prescribed for each of the three frame types (I, S, and U) and the corresponding encoding of the control field are as shown in Table The I-frame command provides the means for transmitting sequentially numbered frames, each of which shall be permitted to contain an information field The S-frame commands and responses shall be used to perform numbered supervisory functions (such as acknowledgement, polling, temporary suspension of information transfer, or error recovery) The receive ready command or response (RR) shall be used by a station to: (a) indicate that it is ready to receive an I-frame; (b) acknowledge previously received I-frames numbered up to and including N(R) 1; (c) clear a busy condition that was initiated by the transmission of RNR. Note. It is permissible for a combined station to use the RR command to solicit a response from the remote combined station with the poll bit set to It shall be permissible to issue a reject command or response (REJ) to request retransmission of frames starting with the I-frame numbered N(R) where: (a) I-frames numbered N(R) 1 and below are acknowledged; (b) additional I-frames pending initial transmission are to be transmitted following the retransmitted I-frame(s); 209

210 (c) only one REJ exception condition, from one given station to another station, shall be established at any given time: another REJ shall not be issued until the first REJ exception condition has been cleared; (d) the REJ exception condition is cleared (reset) upon the receipt of an I-frame with an N(S) count equal to the N(R) of the REJ command/response The receive not ready command or response (RNR) shall be used to indicate a busy condition, i.e. temporary inability to accept additional incoming I-frames, where: (a) frames numbered up to and including N(R) 1 are acknowledged; (b) frame N(R) and any subsequent I-frames received, if any, are not acknowledged (the acceptance status of these frames shall be indicated in subsequent exchanges); (c) the clearing of a busy condition shall be indicated by the transmission of an RR, REJ, SABM, or UA with or without the P/F bit set to (a) A station receiving an RNR frame when in the process of transmitting shall stop transmitting I-frames at the earliest possible time. (b) Any REJ command or response which was received prior to the RNR shall be actioned before the termination of transmission. (c) It shall be permissible for a combined station to use the RNR command with the poll bit set to 1 to obtain a supervisory frame with the final bit set to 1 from the remote combined station It shall be permissible for the selective reject command or response (SREJ) to be used to request retransmission of the single I-frame numbered N(R) where: (a) frames numbered up to N(R) 1 are acknowledged; frame N(R) is not accepted; the only I-frames accepted are those received correctly and in sequence following the I-frame 210

211 requested; the specific I-frame to be retransmitted is indicated by the N(R) in the SREJ command/response; (b) the SREJ exception condition is cleared (reset) upon receipt of an I-frame with an N(S) count equal to the N(R) of the SREJ; (c) after a station transmits a SREJ it is not permitted to transmit SREJ or REJ for an additional sequence error until the first SREJ error condition has been cleared; (d) I-frames that have been permitted to be transmitted following the I-frame indicated by the SREJ are not retransmitted as the result of receiving a SREJ; and (e) it is permissible for additional I-frames pending initial transmission to be transmitted following the retransmission of the specific I-frame requested by the SREJ The U-frame commands and responses shall be used to extend the number of link control functions. Transmitted U-frames do not increment the sequence counts at either the transmitting or receiving station. (a) The U-frame mode-setting commands (SABM, and DISC) shall be used to place the addressed station in the appropriate response mode (ABM or ADM) where: 1. upon acceptance of the command, the station send and receive State variables, V(S) and V(R), are set to zero; 2. the addressed station confirms acceptance at the earliest possible time by transmission of a single unnumbered acknowledgement, UA; 3. previously transmitted frames that are unacknowledged when the command is actioned remain unacknowledged; 4. the DISC command is used to perform a logical disconnect, i.e. to inform the addressed combined station that the transmitting combined station is suspending operation. No information field shall be permitted with the DISC command. (b) The unnumbered acknowledge response (UA) shall be used by a combined station to acknowledge the receipt and acceptance of an unnumbered command. Received 211

212 unnumbered commands are not actioned until the UA response is transmitted. No information field shall be permitted with the UA response. (c) The frame reject response (FRMR), employing the information field described below, shall be used by a combined station in the operational mode (ABM) to report that one of the following conditions resulted from the receipt of a frame without an FCS error: 1. a command/response that is invalid or not implemented; 2. a frame with an information field that exceeds the size of the buffer available; 3. a frame having an invalid N(R) count. Note. An invalid N(R) is a count which points to an I-frame which has previously been transmitted and acknowledged or to an I-frame which has not been transmitted and is not the next sequential I-frame pending transmission. (d) The disconnected mode response (DM) shall be used to report a non-operational status where the station is logically disconnected from the link. No information field shall be permitted with the DM response. Note. The DM response shall be sent to request the remote combined station to issue a mode-setting command or, if sent in response to the reception of a mode-setting command, to inform the remote combined station that the transmitting station is still in ADM and cannot action the mode-setting command EXCEPTION CONDITION REPORTING AND RECOVERY This section specifies the procedures that shall be employed to effect recovery following the detection or occurrence of an exception condition at the link level. Exception conditions described are those situations that may occur as the result of transmission errors, station malfunction, or operational situations. 212

213 Busy condition. A busy condition occurs when a station temporarily cannot receive or continue to receive I-frames due to internal constraints, e.g. due to buffering limitations. The busy condition shall be reported to the remote combined station by the transmission of an RNR frame with the N(R) number of the next I-frame that is expected. It shall be permissible for traffic pending transmission at the busy station to be transmitted prior to or following the RNR. Note. The continued existence of a busy condition must be reported by retransmission of RNR at each P/F frame exchange Upon receipt of an RNR, a combined station in ABM shall cease transmitting I-frames at the earliest possible time by completing or aborting the frame in process. The combined station receiving an RNR shall perform a time-out operation before resuming asynchronous transmission of I-frames unless the busy condition is reported as cleared by the remote combined station. If the RNR was received as a command with the P bit set to 1, the receiving station shall respond with an S-frame with the F bit set to The busy condition shall be cleared at the station which transmitted the RNR when the internal constraint ceases. Clearance of the busy condition shall be reported to the remote station by transmission of an RR, REJ, SABM, or UA frame (with or without the P/F bit set to 1 ) N(S) sequence error. An N(S) sequence exception shall be established in the receiving station when an I-frame that is received error free (no FCS error) contains an N(S) sequence number that is not equal to the receive variable V(R) at the receiving station. The receiving station shall not acknowledge (shall not increment its receive variable V(R)) the frame causing the sequence error, or any I-frames which may follow, until an I- frame with the correct N(S) number is received. A station that receives one or more I-frames having sequence errors, but which are otherwise error free, shall accept the control information contained in the N(R) field and the P/F bit to perform link control functions, e.g. to receive acknowledgement of previously transmitted I-frames (via the N(R)), to cause the station to respond (P bit set to 1 ). 213

214 The means specified in and shall be available for initiating the retransmission of lost or errored I-frames following the occurrence of a sequence error Where the REJ command/response is used to initiate an exception recovery following the detection of a sequence error, only one sent REJ exception condition, from one station to another station, shall be established at a time. A sent REJ exception shall be cleared when the requested I-frame is received. A station receiving REJ shall initiate sequential (re)transmission of I-frames starting with the I- frame indicated by the N(R) contained in the REJ frame. 214

215 FRMR INFORMATION FIELD BITS FOR BASIC (SABM) OPERATION In the event a receiving station, due to a transmission error, does not receive (or receives and discards) a single I-frame or the last I- frame(s) in a sequence of I-frames, it shall not detect an out-ofsequence exception and, therefore, shall not transmit REJ. The station which transmitted the unacknowledged I-frame(s) shall, following the completion of a system-specified time-out period, take appropriate recovery action to determine the sequence number at which retransmission must begin A combined station which has timed out waiting for a response shall not retransmit all unacknowledged frames immediately. The station may enquire about status with a supervisory frame. Note 1. If a station does retransmit all unacknowledged I-frames after a time-out, it must be prepared to receive a subsequent REJ frame with an N(R) greater than its send variable V(S). 215

216 Note 2. Since contention may occur in the case of two-way alternate communications in ABM or ADM, the time-out interval employed by one combined station must be greater than that employed by the other combined station so as to permit contention to be resolved FCS error. Any frame with an FCS error shall not be accepted by the receiving station and will be discarded. No action shall be taken by the receiving station as the result of that frame Frame reject exception condition. A frame reject exception condition shall be established upon the receipt of an error-free frame which contains an invalid or unimplemented control field, an invalid N(R), or an information field which has exceeded the maximum established storage capability. If a frame reject exception condition occurs in a combined station, the station shall either: (a) take recovery action without reporting the condition to the remote combined station; or (b) report the condition to the remote combined station with a FRMR response. The remote station will then be expected to take recovery action; if, after waiting an appropriate time, no recovery action appears to have been taken, the combined station reporting the frame reject exception condition may take recovery action. Recovery action for balanced operation includes the transmission of an implemented mode-setting command. Higher level functions may also be involved in the recovery Mode-setting contention. A mode-setting contention situation exists when a combined station issues a modesetting command and, before receiving an appropriate response (UA or DM), receives a mode-setting command from the remote combined station. Contention situations shall be resolved in the following manner: (a) when the send and receive mode-setting commands are the same, each combined station shall send a UA response at the earliest respond opportunity. Each combined station shall either enter the indicated mode immediately or defer entering the indicated mode until receiving a UA response. In the latter case, if the UA response is not received: 216

217 1. the mode may be entered when the response timer expires; or 2. the mode-setting command may be reissued; (b) when the mode-setting commands are different, each combined station shall enter ADM and issue a DM response at the earliest respond opportunity. In the case of DISC contention with a different mode-setting command, no further action is required Time-out functions. Time-out functions shall be used to detect that a required or expected acknowledging action or response to a previously transmitted frame has not been received. Expiration of the time-out function shall initiate appropriate action, e.g. error recovery or reissuance of the P bit. The duration of the following time-out functions is system dependent and subject to bilateral agreement: (a) combined stations shall provide a time-out function to determine that a response frame with F bit set to 1 to a command frame with the P bit set to 1 has not been received. The time-out function shall automatically cease upon receipt of a valid frame with the F bit set to 1 ; (b) a combined station which has no P bit outstanding, and which has transmitted one or more frames for which responses are anticipated shall start a time-out function to detect the no-response condition. The time-out function shall cease when an I- or S-frame is received with the N(R) higher than the last received N(R) (actually acknowledging one or more I-frames). 217

218 TABLES FOR THE ELEVENTH SCHEDULE 218

219 219

220 220

221 TWELFTH SCHEDULE (Made under regulation 67) A WORLDWIDE SCHEME FOR THE ALLOCATION, ASSIGNMENT AND APPLICATION OF AIRCRAFT ADDRESSES 1. GENERAL 1.1 Global communications, navigation and surveillance systems shall use an individual aircraft address composed of 24 bits. At any one time, no address shall be assigned to more than one aircraft. The assignment of aircraft addresses requires a comprehensive scheme providing for a balanced and expandable distribution of aircraft addresses applicable worldwide. 2. DESCRIPTION OF THE SCHEME 2.1 Table 9-1 provides for blocks of consecutive addresses available to States for assignment to aircraft. Each block is defined by a fixed pattern of the first 4, 6, 9, 12 or 14 bits of the 24-bit address. Thus, blocks of different sizes ( , , , and consecutive addresses, respectively) are made available. 3. MANAGEMENT OF THE SCHEME 3.1 The International Civil Aviation Organization (ICAO) shall administer the scheme so that appropriate international distribution of aircraft addresses can be maintained. 4.0 ALLOCATION OF AIRCRAFT ADDRESSES 4.1 Blocks of aircraft addresses shall be allocated by ICAO to the State of Registry or common mark registering authority. Address allocations to States shall be as shown in Table A State of Registry or common mark registering authority shall notify ICAO when allocation to that State of an additional block of addresses is required for assignment to aircraft 221

222 4.3 In the future management of the scheme, advantage shall be taken of the blocks of aircraft addresses not yet allocated. These spare blocks shall be distributed on the basis of the relevant ICAO region: Addresses starting with bit combination 00100: AFI region Addresses starting with bit combination 00101: SAM region Addresses starting with bit combination 0101: EUR and NAT regions Addresses starting with bit combination 01100: MID region Addresses starting with bit combination 01101: ASIA region Addresses starting with bit combination 1001: NAM and PAC regions Addresses starting with bit combination : CAR region In addition, aircraft addresses starting with bit combinations 1011, 1101 and 1111 have been reserved for future use. 4.4 Any future requirement for additional aircraft addresses shall be accommodated through coordination between ICAO and the States of Registry or common mark registering authority concerned. A request for additional aircraft addresses shall only be made by a registering authority when at least 75 per cent of the number of addresses already allocated to that registering authority have been assigned to aircraft. 4.5 ICAO shall allocate blocks of aircraft addresses to non-contracting States upon request. 5.0 ASSIGNMENT OF AIRCRAFT ADDRESSES 5.1 Using its allocated block of addresses, the State of Registry or common mark registering authority shall assign an individual aircraft address to each suitably equipped aircraft entered on a national or international register (Table 9-1). Note. For an aircraft delivery, the aircraft operator is expected to inform the airframe manufacturer of an address assignment. The airframe manufacturer or other organization responsible for a delivery flight is expected to ensure installation of a correctly assigned address supplied by the State of Registry or common mark registering authority. Exceptionally, a temporary address may be supplied under the arrangements. 5.2 Aircraft addresses shall be assigned to aircraft in accordance with the following principles: 222

223 (a) at any one time, no address shall be assigned to more than one aircraft with the exception of aerodrome surface vehicles on surface movement areas. If such exceptions are applied by the State of Registry, the vehicles which have been allocated the same address shall not operate on aerodromes separated by less than km; (b) only one address shall be assigned to an aircraft, irrespective of the composition of equipment on board. In the case when a removable transponder is shared by several light aviation aircraft such as balloons or gliders, it shall be possible to assign a unique address to the removable transponder. The registers 0816, 2016, 2116, 2216 and 2516 of the removable transponder shall be correctly updated each time the removable transponder is installed in any aircraft; (c) the address shall not be changed except under exceptional circumstances and shall not be changed during flight; (d) when an aircraft changes its State of Registry, the new registering State shall assign the aircraft a new address from its own allocation address block, and the old aircraft address shall be returned to the allocation address block of the State that previously registered the aircraft; (e) the address shall serve only a technical role for addressing and identification of aircraft and shall not be used to convey any specific information; and (f) the addresses composed of 24 ZEROS or 24 ONES shall not be assigned to aircraft Any method used to assign aircraft addresses shall ensure efficient use of the entire address block that is allocated to Uganda. 6 APPLICATION OF AIRCRAFT ADDRESSES 6.1 The aircraft addresses shall be used in applications which require the routing of information to or from individual suitably equipped aircraft. 223

224 Note 1. Examples of such applications are the aeronautical telecommunication network (ATN), SSR Mode S and airborne collision avoidance system (ACAS). Note 2. This Standard does not preclude assigning the aircraft addresses for special applications associated with the general applications defined therein. Examples of such special applications are the utilization of the 24- bit address in a pseudo-aeronautical earth station to monitor the aeronautical mobile-satellite service ground earth station and in the fixed Mode S transponders to monitor the Mode S ground station operation. Address assignments for special applications are to be carried out in conformance with the procedure established by Uganda to manage the 24- bit address assignments to aircraft. 6.2 An address consisting of 24 ZEROs shall not be used for any application. 7 ADMINISTRATION OF THE TEMPORARY AIRCRAFT ADDRESS ASSIGNMENTS 7.1 Temporary addresses shall be assigned to aircraft in exceptional circumstances, such as when operators have been unable to obtain an address from their individual States of Registry or Common Mark Registering Authority in a timely manner. ICAO shall assign temporary addresses from the block ICAO1 shown in Table When requesting a temporary address, the aircraft operator shall supply to ICAO: aircraft identification, type and make of aircraft, name and address of the operator, and an explanation of the reason for the request Upon issuance of the temporary address to the aircraft operators, ICAO shall inform the State of Registry of the issuance of the temporary address, reason and duration. 7.3 The aircraft operator shall: (a) inform the State of Registry of the temporary assignment and reiterate the request for a permanent address; and (b) inform the airframe manufacturer. 7.4 When the permanent aircraft address is obtained from the State of Registry, the operator shall: 224

225 (a) inform ICAO without delay; (b) relinquish his/her temporary address; and (c) arrange for encoding of the valid unique address within 180 calendar days. 7.5 If a permanent address is not obtained within one year, the aircraft operator shall reapply for a new temporary aircraft address. Under no circumstances shall a temporary aircraft address be used by the aircraft operator for over one year. 225

226 226

227 227

228 228

229 229

230 230

231 1. HF DATA LINK PROTOCOL- THIRTEENTH SCHEDULE (Made under regulation 77) Note. The HFDL protocol is a layered protocol and is compatible with the open systems interconnection (OSI) reference model. It permits the HFDL to function as an aeronautical telecommunication network (ATN)-compatible subnetwork. The details of the protocol are described in the Manual on HF Data Link (Doc 9741). 1.1 Physical layer RF characteristics The aircraft and ground stations shall access the physical medium operating in simplex mode FREQUENCY BANDS HFDL installations shall be capable of operating at any single sideband (SSB) carrier (reference) frequency available to the aeronautical mobile (R) service in the band 2.8 to 22 MHz, and in compliance with the relevant provisions of the Radio Regulations. * All tables and figures are located at the end of this chapter CHANNELS Channel utilization shall be in conformity with the table of carrier (reference) frequencies of Appendix 27 to the ITU Radio Regulations TUNING The equipment shall be capable of operating on integral multiples of 1 khz SIDEBAND The sideband used for transmission shall be on the higher side of its carrier (reference) frequency MODULATION 231

232 HFDL shall employ M-ary phase shift keying (M-PSK) to modulate the radio frequency carrier at the assigned frequency. The symbol rate shall be symbols per second ±10 parts per million (i.e symbols per second). The value of M and the information data rate shall be as specified in Table M-PSK CARRIER Note. The number of M-PSK symbols sent, N, defines the length (duration = NT seconds) of the PPDU. These parameters are defined in the Manual on HF Data Link (Doc 9741) PULSE SHAPE The pulse shape, p(t), shall determine the spectral distribution of the transmitted signal. The Fourier transform of the pulse shape, P(f), shall be defined by: where the spectral roll-off parameter, b = 0.31, has been chosen so that the 20 db points of the signal are at SSB carrier (reference) Hz and 232

233 SSB carrier (reference) Hz and the peak-to-average power ratio of the waveform is less than 5 db TRANSMITTER STABILITY The basic frequency stability of the transmitting function shall be better than: (a) ±20 Hz for HFDL aircraft station subsystems; and (b) ±10 Hz for HFDL ground station subsystems RECEIVER STABILITY The basic frequency stability of the receiving function shall be such that, with the transmitting function stability specified in 1.1.6, the overall frequency difference between ground and airborne functions achieved in service does not exceed 70 Hz PROTECTION A 15 db desired to undesired (D/U) signal ratio shall apply for the protection of co-channel assignments for HFDL as follows: (a) data versus data; (b) data versus voice; and (c) voice versus data CLASS OF EMISSION The class of emission shall be 2K80J2DEN ASSIGNED FREQUENCY The HFDL assigned frequency shall be Hz higher than the SSB carrier (reference) frequency. Note. By convention, the HFDL assigned frequency is offset from the SSB carrier (reference) frequency by Hz. 233

234 The HFDL M-PSK carrier of the digital modulation is offset from the SSB carrier (reference) frequency by Hz. The digital modulation is fully contained within the same overall channel bandwidth as the voice signal and complies with the provisions of Appendix 27 to the ITU Radio Regulations EMISSION LIMITS For HFDL aircraft and ground station transmitters, the peak envelope power (Pp) of any emission on any discrete frequency shall be less than the peak envelope power (Pp) of the transmitter in accordance with the following (see Figure 11-1): (a) on any frequency between 1.5 khz and 4.5 khz lower than the HFDL assigned frequency, and on any frequency between 1.5 khz and 4.5 khz higher than the HFDL assigned frequency: at least 30 db; (b) on any frequency between 4.5 khz and 7.5 khz lower than the HFDL assigned frequency, and on any frequency between 4.5 khz and 7.5 khz higher than the HFDL assigned frequency: at least 38 db; and (c) on any frequency lower than 7.5 khz below the HFDL assigned frequency and on any frequency higher than 7.5 khz above the HFDL assigned frequency: 1. HFDL aircraft station transmitters: 43 db; 2. HFDL ground station transmitters up to and including 50 W: [ log10 Pp(W)] db; and 3. HFDL ground station transmitters more than 50 W: 60 db POWER Ground station installations. The peak envelope power (Pp) supplied to the antenna transmission line shall not exceed a maximum value of 6 kw as provided for in Appendix 27 of the Radio Regulations Aircraft station installations. The peak envelope power supplied to the antenna transmission line shall not exceed 400 W, except as provided for in Appendix 27/62 of the Radio Regulations. 234

235 UNDESIRED SIGNAL REJECTION For HFDL aircraft and ground station receivers, undesired input signals shall be attenuated in accordance with the following: (a) on any frequency between fc and (fc 300 Hz), or between (fc Hz) and (fc Hz): at least 35 db below the peak of the desired signal level; and (b) on any frequency below (fc 300 Hz), or above (fc Hz): at least 60 db below the peak of the desired signal level, where fc is the carrier (reference) frequency RECEIVER RESPONSE TO TRANSIENTS The receiving function shall recover from an instantaneous increase in RF power at the antenna terminal of 60 db within 10 milliseconds. The receiving function shall recover from an instantaneous decrease in RF power at the antenna terminal of 60 db within 25 milliseconds. 1.2 Physical layer functions FUNCTIONS The functions provided by the physical layer shall include the following: (a) transmitter and receiver control; (b) transmission of data; and (c) reception of data TRANSMITTER AND RECEIVER CONTROL The HFDL physical layer shall implement the transmitter/receiver switching and frequency tuning as commanded by the link layer. The physical layer shall perform transmitter keying on demand from the link layer to transmit a packet TRANSMITTER TO RECEIVER TURNAROUND TIME The transmitted power level shall decay at least by 10 db within 100 milliseconds after completing a transmission. An HFDL station subsystem shall be capable of receiving and demodulating, with nominal performance, an incoming signal within 200 milliseconds of the start of the subsequent receive slot. 235

236 RECEIVER TO TRANSMITTER TURNAROUND TIME An HFDL station subsystem shall provide nominal output power within plus or minus 1 db to the antenna transmission line within 200 milliseconds of the start of the transmit slot TRANSMISSION OF DATA Transmission of data shall be accomplished using a time division multiple access (TDMA) technique. The HFDL data link ground station subsystems shall maintain TDMA frame and slot synchronization for the HFDL system. To ensure that slot synchronization is maintained, each HF data link modulator shall begin outputting a pre-key segment at the beginning of a time slot plus or minus 10 milliseconds TDMA STRUCTURE Each TDMA frame shall be 32 seconds. Each TDMA frame shall be divided into thirteen equal duration slots as follows: (a) the first slot of each TDMA frame shall be reserved for use by the HFDL ground station subsystem to broadcast link management data in SPDU packets; and (b) the remaining slots shall be designated either as uplink slots, downlink slots reserved for specific HFDL aircraft station subsystems, or as downlink random access slots for use by all HFDL aircraft station subsystems on a contention basis. These TDMA slots shall be assigned on a dynamic basis using a combination of reservation, polling and random access assignments BROADCAST The HFDL ground station subsystem shall broadcast a squitter protocol data unit (SPDU) every 32 seconds on each of its operating frequencies. Note. Details on the TDMA frame and slot structures, pre-key segment, data structures, including the SPDU, are contained in the Manual on HF Data Link (Doc 9741). 236

237 1.2.4 RECEPTION OF DATA FREQUENCY SEARCH Each HFDL aircraft station shall automatically search the assigned frequencies until it detects an operating frequency RECEPTION OF PPDUS The HF data link receiver shall provide the means to detect, synchronize, demodulate and decode PPDUs modulated according to the waveform defined in , subject to the following distortion: (a) the Hz audio carrier offset by plus or minus 70 Hz; (b) discrete and/or diffuse multipath distortion with up to 5 ms multipath spread; (c) multipath amplitude fading with up to 2 Hz two-sided RMS Doppler spread and Rayleigh statistics; and (d) additive Gaussian and broadband impulsive noise with varying amplitude and random arrival times. Note. Reference CCIR Report DECODING OF PPDUS Upon receipt of the preamble segment the receiver shall: (a) detect the beginning of a burst of data; (b) measure and correct the frequency offset between the transmitter and receiver due to Doppler shift and transmitter/receiver frequency offsets; (c) determine the data rate and interleaver settings to use during data demodulation; (d) achieve M-PSK symbol synchronization; and (e) train the equalizer SYNCHRONIZATION Each HFDL aircraft station subsystem shall synchronize its slot timing to that of its corresponding ground station with respect to the reception time of the last received SPDU. 237

238 SPECIFIED PACKET ERROR RATE PERFORMANCE The number of HFDL media access protocol data units (MPDUs) received with one or more bit errors shall not exceed 5 per cent of the total number of MPDUs received, when using a 1.8 second interleaver and under the signalinspace conditions shown in Table The number of HFDL MPDUs received with one or more bit errors shall not exceed 5 per cent of the total number of MPDUs received, when using a 1.8 second interleaver under the conditions shown in Table 11-3a. 1.3 Link layer Note. Details on link layer functions are contained in the Manual on HF Data Link (Doc 9741). The link layer shall provide control functions for the physical layer, link management and data service protocols CONTROL FUNCTIONS The link layer shall pass commands for frequency tuning, transmitter keying and transmitter/receiver switching to the physical layer LINK MANAGEMENT The link layer shall manage TDMA slot assignments, log-on and log-off procedures, ground station and aircraft station TDMA synchronization, and other functions necessary, taking into account message priority, for the establishment and maintenance of communications DATA SERVICE PROTOCOLS The link layer shall support a reliable link service (RLS) protocol and a direct link service (DLS) protocol RLS 238

239 1.5 The RLS protocol shall be used to exchange acknowledged user data packets between aircraft and ground peer link layers DLS The DLS protocol shall be used to broadcast unsegmented uplink high frequency network protocol data units (HFNPDUs) and other HFNPDUs not requiring automatic retransmission by the link layer. 1.4 Sub network layer Note. Details on sub network layer protocols and services are contained in the Manual on HF Data Link (Doc 9741) PACKET DATA The HFDL sub network layer in the HFDL aircraft station subsystem and HFDL ground station subsystem shall provide connection-oriented packet data service by establishing sub network connections between sub network service users CONNECTIVITY NOTIFICATION SERVICE The HFDL sub network layer in the HFDL aircraft station subsystem shall provide the additional connectivity notification service by sending connectivity notification event messages to the attached ATN router CONNECTIVITY NOTIFICATION EVENT MESSAGES The connectivity notification service shall send connectivity notification event messages to the attached ATN router through the sub network access function HFDL SUBNETWORK LAYER FUNCTIONS The HFDL sub network layer in both the HFDL aircraft station subsystem and HFDL ground station subsystem shall include the following three functions: (a) HFDL sub network dependent (HFSND) function; (b) sub network access function; and (c) interworking function. 239

240 HFSND FUNCTION The HFSND function shall perform the HFSND protocol between each pair of HFDL aircraft station subsystems and HFDL ground station subsystems by exchanging HFNPDUs. It shall perform the HFSND protocol aircraft function in the HFDL aircraft station subsystem and the HFSND protocol ground function in the HFDL ground station subsystem SUBNETWORK ACCESS FUNCTION The sub network access function shall perform the ISO 8208 protocol between the HFDL aircraft station subsystem or HFDL ground station subsystem and the attached routers by exchanging ISO 8208 packets. It shall perform the ISO 8208 DCE function in the HFDL aircraft station subsystem and the HFDL ground station subsystem INTERWORKING FUNCTION The interworking function shall provide the necessary harmonization functions between the HFSND, the sub network access and the connectivity notification functions. 240

241 TABLES FOR THIRTEENTH SCHEDULE 241

242 242

243 FIGURES FOR THE THIRTEENTH SCHEDULE 243

244 FOURTEENTH SCHEDULE (Made under regulation 73) UNIVERSAL ACCESS TRANSCEIVER (UAT)- 1. UAT overall system characteristics of aircraft and ground stations Note. Details on technical requirements related to the implementation of UAT SARPs are contained in Part I of the Manual on the Universal Access Transceiver (UAT) (Doc 9861). Part II of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) (in preparation) will provide additional guidance material. 1.1 TRANSMISSION FREQUENCY The transmission frequency shall be 978 MHz. 1.2 FREQUENCY STABILITY The radio frequency of the UAT equipment shall not vary more than ±0.002 per cent (20 ppm) from the assigned frequency. 1.3 TRANSMIT POWER TRANSMIT POWER LEVELS UAT equipment shall operate at one of the power levels shown in Table 12-1* MAXIMUM POWER The maximum equivalent isotropically radiated power (EIRP) for a UAT aircraft or ground station shall not exceed +58 dbm. 244

245 Note. For example, the maximum EIRP listed above could result from the maximum allowable aircraft transmitter power shown in Table 12-1 with a maximum antenna gain of 4 dbi TRANSMIT MASK The spectrum of a UAT ADS-B message transmission modulated with pseudorandom message data blocks (MDB) shall fall within the limits specified in Table 12-2 when measured in a 100 khz bandwidth. Note. Figure 12-1* is a graphical representation of Table SPURIOUS EMISSIONS Spurious emissions shall be kept at the lowest value which the State of the technique and the nature of the service permit. Note. Appendix 3 of the ITU Radio Regulations requires that transmitting stations shall conform to the maximum permitted power levels for spurious emissions or for unwanted emissions in the spurious domain. 1.5 POLARIZATION * All tables and figures are located at the end of the chapter. The design polarization of emissions shall be vertical. 1.6 TIME/AMPLITUDE PROFILE OF UAT MESSAGE TRANSMISSION The time/amplitude profile of a UAT message transmission shall meet the following requirements, in which the reference time is defined as the beginning of the first bit of the synchronization sequence appearing at the output port of the equipment. Notes. 1. All power requirements for subparagraphs a through f below apply to the PMP. For installations that support transmitter diversity, the RF power output on the non-selected antenna port should be at least 20 db below the level on the selected port. 245

246 2. All power requirements for subparagraphs a and f assume a 300 khz measurement bandwidth. All power requirements for subparagraphs b, c, d and e assume a 2 MHz measurement bandwidth. 3. The beginning of a bit is 1/2 bit period prior to the optimum sample point. 4. These requirements are depicted graphically in Figure (a) Prior to 8 bit periods before the reference time, the RF output power at the PMP shall not exceed 80 dbm. Note. This unwanted radiated power restriction is necessary to ensure that the UAT transmitting subsystem does not prevent closely located UAT receiving equipment on the same aircraft from meeting its requirements. It assumes that the isolation between transmitter and receiver equipment at the PMP exceeds 20 db. (b) Between 8 and 6 bit periods prior to the reference time, the RF output power at the PMP shall remain at least 20 db below the minimum power requirement for the UAT equipment class. Note. Guidance on definition of UAT equipment classes will be provided in Part II of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) (in preparation). (c) During the Active State, defined as beginning at the reference time and continuing for the duration of the message, the RF output power at the PMP shall be greater than or equal to the minimum power requirement for the UAT equipment class. (d) The RF output power at the PMP shall not exceed the maximum power for the UAT equipment class at any time during the Active State. (e) Within 6 bit periods after the end of the Active State, the RF output power at the PMP shall be at a level at least 20 db below the minimum power requirement for the UAT equipment class. (f) Within 8 bit periods after the end of the Active State, the RF output power at the PMP shall fall to a level not to exceed 80 dbm. 246

247 Note. This unwanted radiated power restriction is necessary to ensure that the transmitting subsystem does not prevent closely located UAT receiving equipment on the same aircraft from meeting its requirements. It assumes that the isolation between transmitter and receiver equipment at the PMP exceeds 20 db. 2. SYSTEM CHARACTERISTICS OF UNIVERSAL ACCESS TRANSCEIVER GROUND INSTALLATION 2.1 Ground station transmitting function GROUND STATION TRANSMITTER POWER The effective radiated power shall be such as to provide a field strength of at least 280 microvolts per metre (minus 97 dbw/m2) within the service volume of the facility on the basis of free-space propagation. Note. This is determined on the basis of delivering a 91 dbm (corresponds to 200 microvolts per metre) signal level at the PMP (assuming an omnidirectional antenna). The 280 μv/m standard corresponds to the delivery of a -88 dbm signal level at the PMP of the receiving equipment. The 3 db difference between 88 dbm and 91 dbm provides margin for excess path loss over free-space propagation. 2.2 Ground station receiving function Note. An example ground station receiver is discussed in Section 2.5 of Part II of the Manual on the Universal Access Transceiver (UAT) (Doc 9861), with UAT air-to-ground performance estimates consistent with use of that receiver providedin Appendix B of that manual. 3. SYSTEM CHARACTERISTICS OF THE AIRCRAFT INSTALLATION 3.1 Aircraft transmitting function AIRCRAFT TRANSMITTER POWER 247

248 The effective radiated power shall be such as to provide a field strength of at least 225 microvolts per metre (minus 99 dbw/m2) on the basis of free-space propagation, at ranges and altitudes appropriate to the operational conditions pertaining to the areas over which the aircraft is operated. Transmitter power shall not exceed 54 dbm at the PMP. Note 1. The above field strength is determined on the basis of delivering a 93 dbm (corresponds to 160 microvolts per metre) signal level at the PMP (assuming an omnidirectional antenna). The 3 db difference between 225 μv/m and 160 μv/m provides margin for excess path loss over free-space propagation when receiving a long UAT ADS- B message. A 4 db margin is provided when receiving a basic UAT ADS- B message. Note 2. Various aircraft operations may have different air-air range requirements depending on the intended ADS-B function of the UAT equipment. Therefore different installations may operate at different power levels. 3.2 Receiving function RECEIVER SENSITIVITY LONG UAT ADS-B MESSAGE AS DESIRED SIGNAL A desired signal level of 93 dbm applied at the PMP shall produce a rate of successful message reception (SMR) of 90 per cent or better under the following conditions: (a) When the desired signal is of nominal modulation (i.e. FM deviation is 625 khz) and at the maximum signal frequency offsets, and subject to relative Doppler shift at ±1 200 knots; (b) When the desired signal is of maximum modulation distortion allowed in , at the nominal transmission frequency ±1 parts per million (ppm), and subject to relative Doppler shift at ±1 200 knots. 248

249 Note. The receiver criteria for successful message reception of UAT ADS-B messages are provided in Section 4 of Part I of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) BASIC UAT ADS-B MESSAGE AS DESIRED SIGNAL A desired signal level of 94 dbm applied at the PMP shall produce a rate of SMR of 90 per cent or better under the following conditions: (a) When the desired signal is of nominal modulation (i.e. FM deviation is 625 khz) and at the maximum signal frequency offsets, and subject to relative Doppler shift at ±1 200 knots; (b) When the desired signal is of maximum modulation distortion allowed in , at the nominal transmission frequency ±1 ppm, and subject to relative Doppler shift at ±1 200 knots. Note. The receiver criteria for successful message reception of UAT ADS-B messages are provided in Section 4 of Part I of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) UAT GROUND UPLINK MESSAGE AS DESIRED SIGNAL A desired signal level of 91 dbm applied at the PMP shall produce a rate of an SMR of 90 per cent or better under the following conditions: (a) When the desired signal is of nominal modulation (i.e. FM deviation is 625 khz) and at the maximum signal frequency offsets, and subject to relative Doppler shift at ±850 knots; (b) When the desired signal is of maximum modulation distortion allowed in , at the nominal transmission frequency ±1 ppm, and subject to relative Doppler shift at ±850 knots. 249

250 Notes.- 1. The receiver criteria for successful message reception of UAT ground uplink messages are provided in Section 4 of Part I of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) (in preparation). 2. This requirement ensures the bit rate accuracy supporting demodulation in the UAT equipment is adequate to properly receive the longer UAT ground uplink message RECEIVER SELECTIVITY Notes. 1. The undesired signal used is an unmodulated carrier applied at the frequency offset. 2. This requirement establishes the receiver s rejection of the off-channel energy. 3. It is assumed that ratios in between the specified offsets will fall near the interpolated value. 4. The desired signal used is a UAT ADS-B long message at -90 dbm at the PMP, to be received with a 90 per cent successful message reception rate. 5. The tolerable co-channel continuous wave interference power level for aircraft UAT receivers is assumed to be -101 dbm or less at the PMP. 6. See Section of Part II of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) for a discussion of when a highperformance receiver is desirable. a) Standard UAT receivers shall meet the selectivity characteristics given in Table b) High-performance receivers shall meet the more stringent selectivity characteristics given in Table Note. See Section of Part II of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) for guidance material on the implementation of high-performance receivers. 250

251 3.2.3 RECEIVER DESIRED SIGNAL DYNAMIC RANGE The receiver shall achieve a successful message reception rate for long ADS-B messages of 99 per cent or better when the desired signal level is between 90 dbm and 10 dbm at the PMP in the absence of any interfering signals. Note. The value of 10 dbm represents 120-foot separation from an aircraft transmitter transmitting at maximum allowed power RECEIVER TOLERANCE TO PULSED INTERFERENCE Note. All power level requirements in this section are referenced to the PMP. (a) For Standard and High-Performance receivers the following requirements shall apply: 1. The receiver shall be capable of achieving 99 per cent SMR of long UAT ADS-B messages when the desired signal level is between 90 dbm and 10 dbm when subjected to DME interference under the following conditions: DME pulse pairs at a nominal rate of pulse pairs per second at either 12 or 30 microseconds pulse spacing at a level of 36 dbm for any 1 MHz DME channel frequency between 980 MHz and MHz inclusive. 2. Following a 21 microsecond pulse at a level of ZERO (0) dbm and at a frequency of MHz, the receiver shall return to within 3 db of the specified sensitivity level (see ) within 12 microseconds. (b) For the standard UAT receiver the following additional requirements shall apply: 1. The receiver shall be capable of achieving 90 per cent SMR of long UAT ADS-B messages when the desired signal level is between 87 dbm and 10 dbm when subjected to DME interference under the following conditions: DME pulse pairs at a nominal rate of

252 pulse pairs per second at a 12 microseconds pulse spacing at a level of 56 dbm and a frequency of 979 MHz. 2. The receiver shall be capable of achieving 90 per cent SMR of long UAT ADS-B messages when the desired signal level is between 87 dbm and 10 dbm when subjected to DME interference under the following conditions: DME pulse pairs at a nominal rate of pulse pairs per second at a 12 microseconds pulse spacing at a level of 70 dbm and a frequency of 978 MHz. (c) For the high-performance receiver the following additional requirements shall apply: 1. The receiver shall be capable of achieving 90 per cent SMR of long UAT ADS-B messages when the desired signal level is between 87 dbm and 10 dbm when subjected to DME interference under the following conditions: DME pulse pairs at a nominal rate of pulse pairs per second at a 12 microseconds pulse spacing at a level of 43 dbm and a frequency of 979 MHz. 2. The receiver shall be capable of achieving 90 per cent SMR of long UAT ADS-B messages when the desired signal level is between 87 dbm and 10 dbm when subjected to DME interference under the following conditions: DME pulse pairs at a nominal rate of pulse pairs per second at a 12 microseconds pulse spacing at a level of 79 dbm and a frequency of 978 MHz. 4. PHYSICAL LAYER CHARACTERISTICS 4.1 Modulation rate The modulation rate shall be Mbps with a tolerance for aircraft transmitters of ±20 ppm and a tolerance for ground transmitters of ±2 ppm. Note.- The tolerance on the modulation rate is consistent with the requirement on modulation distortion. 252

253 4.2 Modulation type (a) Data shall be modulated onto the carrier using binary continuous phase frequency shift keying. The modulation index, h, shall be no less than 0.6; (b) A binary ONE (1) shall be indicated by a shift up in frequency from the nominal carrier frequency and a binary ZERO (0) by a shift down from the nominal carrier frequency. Notes. 1. Filtering of the transmitted signal (at base band and/or after frequency modulation) will be required to meet the spectral containment requirement of This filtering may cause the deviation to exceed these values at points other than the optimum sampling points. Because of the filtering of the transmitted signal, the received frequency offset varies continuously between the nominal values of ±312.5 khz (and beyond), and the optimal sampling point may not be easily identified. This point can be defined in terms of the so-called eye diagram of the received signal. The ideal eye diagram is a superposition of samples of the (undistorted) post detection waveform shifted by multiples of the bit period (0.96 microseconds). The optimum sampling point is the point during the bit period at which the opening of the eye diagram (i.e. the minimum separation between positive and negative frequency offsets at very high signal-to-noise ratios) is maximized. An example eye diagram can be seen in Figure The timing of the points where the lines converge defines the optimum sampling point. Figure 12-4 shows an eye pattern that has been partially closed by modulation distortion. 4.3 Modulation distortion (a) For aircraft transmitters, the minimum vertical opening of the eye diagram of the transmitted signal (measured at the optimum sampling points) shall be no less than 560 khz when measured over an entire long UAT ADS-B message containing pseudorandom message data blocks. (b) For ground transmitters, the minimum vertical opening of the eye diagram of the transmitted signal (measured at the optimum sampling points) shall be no less than 560 khz when measured 253

254 over an entire UAT ground uplink message containing pseudorandom message data blocks. (c) For aircraft transmitters, the minimum horizontal opening of the eye diagram of the transmitted signal (measured at 978 MHz) shall be no less than microseconds (0.65 symbol periods) when measured over an entire long UAT ADS-B message containing pseudorandom message data blocks. (d) For ground transmitters, the minimum horizontal opening of the eye diagram of the transmitted signal (measured at 978 MHz) shall be no less than microseconds (0.65 symbol periods) when measured over an entire UAT ground uplink message containing pseudorandom message data blocks. 4.4 Broadcast message characteristics The UAT system shall support two different message types: the UAT ADS-B message and the UAT ground uplink message UAT ADS-B MESSAGE The Active portion of a UAT ADS-B message shall contain the following elements, in the following order: - Bit synchronization - Message data block - FEC parity BIT SYNCHRONIZATION The first element of the Active portion of the UAT ADS-B message shall be a 36-bit synchronization sequence. For the UAT ADS-B messages the sequence shall be: with the left-most bit transmitted first THE MESSAGE DATA BLOCK The second element of the Active portion of the UAT ADS-B message shall be the message data block. There shall be two lengths of UAT ADS-B message data blocks supported. The basic UAT ADS-B message 254

255 shall have a 144-bit message data block and the long UAT ADS-B message shall have a 272-bit message data block. Note. The format, encoding and transmission order of the message data block element is provided in Section 2.1 of Part I of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) FEC PARITY The third and final element of the Active portion of the UAT ADS-B message shall be the FEC parity Code type The FEC parity generation shall be based on a systematic Reed-Solomon (RS) 256-ary code with 8-bit code word symbols. FEC parity generation shall be per the following code: (a) Basic UAT ADS-B message: Parity shall be a RS (30, 18) code. Note. This results in 12 bytes (code symbols) of parity capable of correcting up to 6 symbol errors per block. (b) Long UAT ADS-B message: Parity shall be a RS (48, 34) code. For either message length the primitive polynomial of the code shall be as follows: The generator polynomial shall be as follows: 255

256 where: P = 131 for RS (30, 18) code, P = 133 for RS (48, 34) code, and α is a primitive element of a Galois field of size 256 (i.e. GF(256)) Transmission order of FEC parity FEC parity bytes shall be ordered most significant to least significant in terms of the polynomial coefficients they represent. The ordering of bits within each byte shall be most significant to least significant. FEC parity bytes shall follow the message data block UAT GROUND UPLINK MESSAGE The Active portion of a UAT ground uplink message shall contain the following elements, in the following order: - Bit synchronization - Interleaved message data block and FEC parity BIT SYNCHRONIZATION The first element of the Active portion of the UAT ground uplink message shall be a 36-bit synchronization sequence. For the UAT ground uplink message the sequence shall be: with the left-most bit transmitted first INTERLEAVED MESSAGE DATA BLOCK AND FEC PARITY Message data block (before interleaving and after de-interleaving) The UAT ground uplink message shall have bits of message data block. These bits are divided into 6 groups of 576 bits. FEC is applied to each group 256

257 Note. Further details on the format, encoding and transmission order of the UAT ground uplink message data block are provided in Section 2.2 of Part I of the Manual on the Universal Access Transceiver (UAT) (Doc 9861) FEC parity (before interleaving and after de-interleaving) Code type The FEC parity generation shall be based on a systematic RS 256-ary code with 8-bit code word symbols. FEC parity generation for each of the six blocks shall be a RS (92,72) code. Notes. 1. Section provides details on the interleaving procedure. 2. This results in 20 bytes (symbols) of parity capable of correcting up to 10 symbol errors per block. The additional use of interleaving for the UAT ground uplink message allows additional robustness against burst errors. The primitive polynomial of the code is as follows: The generator polynomial is as follows: where: P = 139, and α is a primitive element of a Galois field of size 256 (i.e. GF(256)) Transmission order of FEC parity FEC parity bytes are ordered most significant to least significant in terms of the polynomial coefficients they represent. The ordering of bits within 257

258 each byte shall be most significant to least significant. FEC parity bytes shall follow the message data block Interleaving procedure UAT ground uplink messages shall be interleaved and transmitted by the ground station, as listed below: (a) Interleaving procedure: The interleaved message data block and FEC parity consists of 6 interleaved Reed- Solomon blocks. The interleaver is represented by a 6 92 matrix, where each entry is a RS 8-bit symbol. Each row comprises a single RS (92,72) block as shown in Table In this table, block numbers prior to interleaving are represented as A through F. The information is ordered for transmission column by column, starting at the upper left corner of the matrix. (b) Transmission order: The bytes are then transmitted in the following order: 1,73,145,217,289,361,2,74,146,218,290,362,3,...,C/20,D/20,E/20,F/20. Note. On reception these bytes need to be de-interleaved so that the RS blocks can be reassembled prior to error correction decoding. 5. GUIDANCE MATERIAL Notes. 1. The Manual on the Universal Access Transceiver (UAT) (Doc 9861), Part I, provides detailed technical specifications on UAT, including ADS-B message data blocks and formats, procedures for operation of UAT transmitting subsystems, and avionics interface requirements with other aircraft systems. 2. The Manual on the Universal Access Transceiver (UAT) (Doc 9861), Part II, provides information on UAT system operation, description of a range of example avionics equipment classes and their applications, guidance on UAT aircraft and ground station installation aspects, and detailed information on UAT system performance simulation. 258

259 TABLES FOR CHAPTER

260 260

261 261

262 262

263 263

Aeronautical Telecommunications

Aeronautical Telecommunications International Standards and Recommended Practices Annex 10 to the Convention on International Civil Aviation Aeronautical Telecommunications Volume III Communication Systems (Part I Digital Data Communication

More information

ETSI TS V1.1.1 ( ) Technical Specification

ETSI TS V1.1.1 ( ) Technical Specification TS 101 535 V1.1.1 (2010-12) Technical Specification VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment 2 TS 101 535

More information

THE CIVIL AVIATION ACT (NO 21 OF 2013) REGULATIONS DRAFT CIVIL AVIATION (SURVEILLANCE AND COLLISION AVOIDANCE SYSTEMS) REGULATIONS, 2017.

THE CIVIL AVIATION ACT (NO 21 OF 2013) REGULATIONS DRAFT CIVIL AVIATION (SURVEILLANCE AND COLLISION AVOIDANCE SYSTEMS) REGULATIONS, 2017. LEGAL NOTICE. THE CIVIL AVIATION ACT (NO 21 OF 2013) REGULATIONS DRAFT CIVIL AVIATION (SURVEILLANCE AND COLLISION AVOIDANCE SYSTEMS) REGULATIONS, 2017. ARRANGEMENT OF REGULATIONS Regulation PART I PRELIMINARY

More information

International Civil Aviation Organization

International Civil Aviation Organization Doc 9688 AN/952 Manual on Mode S Specific Services Approved by the Secretary General and published under his authority Second Edition 2004 International Civil Aviation Organization AMENDMENTS Amendments

More information

THE CIVIL AVIATION ACT, (CAP. 80) ARRANGEMENT OF REGULATIONS PART I PRELIMINARY PROVISIONS PART II GENERAL REQUIREMENTS

THE CIVIL AVIATION ACT, (CAP. 80) ARRANGEMENT OF REGULATIONS PART I PRELIMINARY PROVISIONS PART II GENERAL REQUIREMENTS GOVERNMENT NOTICE NO. 72 published on 24/02/2017 THE CIVIL AVIATION ACT, (CAP. 80) THE CIVIL AVIATION (SURVEILLANCE AND COLLISION AVOIDANCE SYSTEMS) REGULATIONS, 2017 1. Citation 2. Interpretation 3. Application

More information

MYANMAR CIVIL AVIATION REQUIREMENTS

MYANMAR CIVIL AVIATION REQUIREMENTS Civil Aviation Requirements THE REPULBIC OF THE UNION OF MYANMAR MINISTRY OF TRANSPORT DEPARTMENT OF CIVIL AVIATION MYANMAR CIVIL AVIATION REQUIREMENTS MCAR Part-5 ANS Section 9 Volume-V Aeronautical Telecommunications

More information

Subject: Aeronautical Telecommunications Aeronautical Radio Frequency Spectrum Utilization

Subject: Aeronautical Telecommunications Aeronautical Radio Frequency Spectrum Utilization GOVERNMENT OF INDIA OFFICE OF DIRECTOR GENERAL OF CIVIL AVIATION TECHNICAL CENTRE, OPP SAFDARJANG AIRPORT, NEW DELHI CIVIL AVIATION REQUIREMENTS SECTION 4 - AERODROME STANDARDS & AIR TRAFFIC SERVICES SERIES

More information

ETSI EN V1.4.1 ( )

ETSI EN V1.4.1 ( ) EN 301 842-1 V1.4.1 (2015-04) EUROPEAN STANDARD VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment; Part 1: EN for

More information

Technical Provisions for Mode S Services and Extended Squitter

Technical Provisions for Mode S Services and Extended Squitter Doc 9871 AN/460 Technical Provisions for Mode S Services and Extended Squitter Notice to Users This document is an unedited advance version of an ICAO publication as approved, in principle, by the Secretary

More information

Regulations. Aeronautical Radio Service

Regulations. Aeronautical Radio Service Regulations Aeronautical Radio Service Version 1.0 Issue Date: 30 December 2009 Copyright 2009 Telecommunications Regulatory Authority (TRA). All rights reserved. P O Box 26662, Abu Dhabi, United Arab

More information

ETSI EN V2.1.1 ( )

ETSI EN V2.1.1 ( ) HARMONISED EUROPEAN STANDARD VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment; Part 5: Harmonised Standard covering

More information

AMCP WG-D/9 WP/2. EUROCAE Document ED-xx MINIMUM OPERATIONAL PERFORMANCE SPECIFICATION FOR VDL MODE 4 AIRCRAFT TRANSCEIVER

AMCP WG-D/9 WP/2. EUROCAE Document ED-xx MINIMUM OPERATIONAL PERFORMANCE SPECIFICATION FOR VDL MODE 4 AIRCRAFT TRANSCEIVER AMCP WG-D/9 WP/2 EUROCAE Document ED-xx MINIMUM OPERATIONAL PERFORMANCE SPECIFICATION FOR VDL MODE 4 AIRCRAFT TRANSCEIVER Working DRAFT D August 1998 FOREWORD 1. This document, prepared by EUROCAE Working

More information

ICAO SARPS AND GUIDANCE DOCUMENTS ON SURVEILLANCE SYSTEMS

ICAO SARPS AND GUIDANCE DOCUMENTS ON SURVEILLANCE SYSTEMS ICAO SARPS AND GUIDANCE DOCUMENTS ON SURVEILLANCE SYSTEMS MEETING/WORKSHOP ON AUTOMATIC DEPENDENT SURVEILLANCE BROADCAST (ADS B) IMPLEMENTATION (ADS B/IMP) (Lima, Peru, 13 to 16 November 2017) ONOFRIO

More information

RECOMMENDATION ITU-R BS

RECOMMENDATION ITU-R BS Rec. ITU-R BS.1350-1 1 RECOMMENDATION ITU-R BS.1350-1 SYSTEMS REQUIREMENTS FOR MULTIPLEXING (FM) SOUND BROADCASTING WITH A SUB-CARRIER DATA CHANNEL HAVING A RELATIVELY LARGE TRANSMISSION CAPACITY FOR STATIONARY

More information

SECTION 2 BROADBAND RF CHARACTERISTICS. 2.1 Frequency bands

SECTION 2 BROADBAND RF CHARACTERISTICS. 2.1 Frequency bands SECTION 2 BROADBAND RF CHARACTERISTICS 2.1 Frequency bands 2.1.1 Use of AMS(R)S bands Note.- Categories of messages, and their relative priorities within the aeronautical mobile (R) service, are given

More information

ETSI EN V1.1.1 ( )

ETSI EN V1.1.1 ( ) EN 301 842-2 V1.1.1 (2002-08) European Standard (Telecommunications series) Electromagnetic compatibility and Radio spectrum Matters (ERM); VHF air-ground Data Link (VDL) Mode 4 radio equipment; Technical

More information

ETSI EN V1.7.1 ( )

ETSI EN V1.7.1 ( ) EN 301 842-2 V1.7.1 (2015-04) EUROPEAN STANDARD VHF air-ground Digital Link (VDL) Mode 4 radio equipment; Technical characteristics and methods of measurement for ground-based equipment; Part 2: General

More information

Band Class Specification for cdma2000 Spread Spectrum Systems

Band Class Specification for cdma2000 Spread Spectrum Systems GPP C.S00-B Version.0 Date: August, 00 Band Class Specification for cdma000 Spread Spectrum Systems Revision B COPYRIGHT GPP and its Organizational Partners claim copyright in this document and individual

More information

Band Class Specification for cdma2000 Spread Spectrum Systems

Band Class Specification for cdma2000 Spread Spectrum Systems GPP C.S00 Version.0 Date: February, 00 Band Class Specification for cdma000 Spread Spectrum Systems Revision 0 COPYRIGHT GPP and its Organizational Partners claim copyright in this document and individual

More information

Seychelles Civil Aviation Authority SAFETY NOTICE. Coding and registration of Seychelles 406 Mhz Emergency Locator Transmitters (ELTs)

Seychelles Civil Aviation Authority SAFETY NOTICE. Coding and registration of Seychelles 406 Mhz Emergency Locator Transmitters (ELTs) Seychelles Civil Aviation Authority Safety Notice SAFETY NOTICE Number: Issued: 25 April 2018 Coding and registration of Seychelles 406 Mhz Emergency Locator Transmitters (ELTs) This Safety Notice contains

More information

TECHNICAL CONDITIONS FOR RADIO EQUIPMENT OF INMARSAT SHIP EARTH STATIONS, etc

TECHNICAL CONDITIONS FOR RADIO EQUIPMENT OF INMARSAT SHIP EARTH STATIONS, etc TECHNICAL CONDITIONS FOR RADIO EQUIPMENT OF INMARSAT SHIP EARTH STATIONS, etc (Article 7 paragraph 21, Article 14 paragraph 3, Article 40.4 paragraph 1 item 5, Article 40.4 paragraph 2 item 4, Article

More information

GOVERNMENT OF INDIA OFFICE OF DIRECTOR GENERAL OF CIVIL AVIATION TECHNICAL CENTRE, OPP SAFDARJANG AIRPORT, NEW DELHI

GOVERNMENT OF INDIA OFFICE OF DIRECTOR GENERAL OF CIVIL AVIATION TECHNICAL CENTRE, OPP SAFDARJANG AIRPORT, NEW DELHI GOVERNMENT OF INDIA OFFICE OF DIRECTOR GENERAL OF CIVIL AVIATION TECHNICAL CENTRE, OPP SAFDARJANG AIRPORT, NEW DELHI CIVIL AVIATION REQUIREMENTS SECTION 9 AIR SPACE AND AIR TRAFFIC MANAGEMENT SERIES 'D',

More information

Newcomers and Elmers Net: What Else can you do with a Soundcard Robert AK3Q

Newcomers and Elmers Net: What Else can you do with a Soundcard Robert AK3Q Newcomers and Elmers Net: What Else can you do with a Soundcard Robert AK3Q 4-12-15 Sound card modes Beacons (NDBs-non-directional beacons) as well as amateur radio beacons in the 475 khz range plane plotter

More information

0.6 kbits/s, the modulation shall be aviation binary phase shift keying (A-BPSK).

0.6 kbits/s, the modulation shall be aviation binary phase shift keying (A-BPSK). SECTION 3 RF CHANNEL CHARACTERISTICS 3.1 Modulation 3.1.1 Modulation for channel rates 2.4 kbits/s and below. For channel rates of 2.4, 1.2 and 0.6 kbits/s, the modulation shall be aviation binary phase

More information

INTERNATIONAL TELECOMMUNICATION UNION DATA COMMUNICATION NETWORK: INTERFACES

INTERNATIONAL TELECOMMUNICATION UNION DATA COMMUNICATION NETWORK: INTERFACES INTERNATIONAL TELECOMMUNICATION UNION CCITT X.21 THE INTERNATIONAL (09/92) TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE DATA COMMUNICATION NETWORK: INTERFACES INTERFACE BETWEEN DATA TERMINAL EQUIPMENT

More information

AIR NAVIGATION ORDER

AIR NAVIGATION ORDER (AERONAUTICAL RADIO FREQUENCY SPECTRUM UTILIZATION) AIR NAVIGATION ORDER [[ VERSION : 1.0 DATE OF IMPLEMENTATION : 15-12-2010 OFFICE OF PRIME INTEREST : Technical Standards (DAAR) 15/12/2010 ANO-006-DRTS-1.0

More information

UK Interface Requirement 2060

UK Interface Requirement 2060 UK Interface Requirement 2060 Ground based VHF radio equipment at Aeronautical Stations of the Aeronautical Mobile (R) Service for Mode 2 and/or Mode 4 data link communications. Publication date: Feb 2006

More information

Working Party 5B DRAFT NEW RECOMMENDATION ITU-R M.[500KHZ]

Working Party 5B DRAFT NEW RECOMMENDATION ITU-R M.[500KHZ] Radiocommunication Study Groups Source: Subject: Document 5B/TEMP/376 Draft new Recommendation ITU-R M.[500kHz] Document 17 November 2011 English only Working Party 5B DRAFT NEW RECOMMENDATION ITU-R M.[500KHZ]

More information

SECTION 4 CHANNEL FORMAT TYPES AND RATES. 4.1 General

SECTION 4 CHANNEL FORMAT TYPES AND RATES. 4.1 General SECTION 4 CHANNEL FORMAT TYPES AND RATES 4.1 General 4.1.1 Aircraft system-timing reference point. The reference timing point for signals generated and received by the AES shall be at the antenna. 4.1.2

More information

Organización de Aviación Civil Internacional. Международная организация гражданской авиации. Ref.: AN 7/ /78 27 November 2015

Organización de Aviación Civil Internacional. Международная организация гражданской авиации. Ref.: AN 7/ /78 27 November 2015 International Civil Aviation Organization Organisation de l aviation civile internationale Organización de Aviación Civil Internacional Международная организация гражданской авиации Tel.: +1 514-954-8219

More information

10 Secondary Surveillance Radar

10 Secondary Surveillance Radar 10 Secondary Surveillance Radar As we have just noted, the primary radar element of the ATC Surveillance Radar System provides detection of suitable targets with good accuracy in bearing and range measurement

More information

INTERNATIONAL STANDARDS AND RECOMMENDED PRACTICES

INTERNATIONAL STANDARDS AND RECOMMENDED PRACTICES Annex or Recommended Practice Chapter 1 Definition INTERNATIONAL STANDARDS AND RECOMMENDED PRACTICES CHAPTER 1. DEFINITIONS N1.All references to Radio Regulations are to the Radio Regulations published

More information

EE Limited - Public Wireless Network Licence Company Registration no First Issued: 26/03/93 - Licence Number: Rev: 20-10/01/17

EE Limited - Public Wireless Network Licence Company Registration no First Issued: 26/03/93 - Licence Number: Rev: 20-10/01/17 Office of Communications (Ofcom) Wireless Telegraphy Act 2006 EE Limited - Public Wireless Network Licence PUBLIC WIRELESS NETWORK LICENCE This Licence document replaces the version of the Licence issued

More information

Aeronautical Telecommunications

Aeronautical Telecommunications International Standards and Recommended Practices Annex 10 to the Convention on International Civil Aviation Aeronautical Telecommunications Volume IV Surveillance and Collision Avoidance Systems This

More information

HD Radio FM Transmission. System Specifications

HD Radio FM Transmission. System Specifications HD Radio FM Transmission System Specifications Rev. G December 14, 2016 SY_SSS_1026s TRADEMARKS HD Radio and the HD, HD Radio, and Arc logos are proprietary trademarks of ibiquity Digital Corporation.

More information

SATELLITE NETWORK NOTIFICATION AND COORDINATION REGULATIONS 2007 BR 94/2007

SATELLITE NETWORK NOTIFICATION AND COORDINATION REGULATIONS 2007 BR 94/2007 BR 94/2007 TELECOMMUNICATIONS ACT 1986 1986 : 35 SATELLITE NETWORK NOTIFICATION AND COORDINATION ARRANGEMENT OF REGULATIONS 1 Citation 2 Interpretation 3 Purpose 4 Requirement for licence 5 Submission

More information

RECOMMENDATION ITU-R M.541-8*

RECOMMENDATION ITU-R M.541-8* Rec. ITU-R M.541-8 1 RECOMMENDATION ITU-R M.541-8* OPERATIONAL PROCEDURES FOR THE USE OF DIGITAL SELECTIVE-CALLING EQUIPMENT IN THE MARITIME MOBILE SERVICE (Question ITU-R 9/8) (1978-1982-1986-1990-1992-1994-1995-1996-1997)

More information

Guidance Material for ILS requirements in RSA

Guidance Material for ILS requirements in RSA Guidance Material for ILS requirements in RSA General:- Controlled airspace required with appropriate procedures. Control Tower to have clear and unobstructed view of the complete runway complex. ATC to

More information

This Licence document replaces the version of the Licence issued by the Office of Communications (Ofcom) on 23 March 2015 to EE Limited.

This Licence document replaces the version of the Licence issued by the Office of Communications (Ofcom) on 23 March 2015 to EE Limited. Office of Communications (Ofcom) Wireless Telegraphy Act 2006 SPECTRUM ACCESS 800 MHz / 2.6 GHz LICENCE This Licence document replaces the version of the Licence issued by the Office of Communications

More information

Radiocommunications Regulations (General User Radio Licence for Aeronautical Purposes) Notice 2016

Radiocommunications Regulations (General User Radio Licence for Aeronautical Purposes) Notice 2016 Radiocommunications Regulations (General User Radio Licence for Aeronautical Purposes) Notice 2016 Pursuant to section 111 of the Radiocommunications Act 1989 and Regulation 9 of the Radiocommunications

More information

TRANSMITTAL NOTE NEW EDITIONS OF ANNEXES TO THE CONVENTION ON INTERNATIONAL CIVIL AVIATION

TRANSMITTAL NOTE NEW EDITIONS OF ANNEXES TO THE CONVENTION ON INTERNATIONAL CIVIL AVIATION TRANSMITTAL NOTE NEW EDITIONS OF ANNEXES TO THE CONVENTION ON INTERNATIONAL CIVIL AVIATION It has come to our attention that when a new edition of an Annex is published, users have been discarding, along

More information

ICAO HANDBOOK ON RADIO FREQUENCY SPECTRUM REQUIREMENTS FOR CIVIL AVIATION

ICAO HANDBOOK ON RADIO FREQUENCY SPECTRUM REQUIREMENTS FOR CIVIL AVIATION Doc 9718 Volume II First Edition Amendment ICAO HANDBOOK ON RADIO FREQUENCY SPECTRUM REQUIREMENTS FOR CIVIL AVIATION Volume II Frequency assignment planning criteria for aeronautical radio communication

More information

Subject: Aeronautical Telecommunications Digital Data Communication and Voice Communication System

Subject: Aeronautical Telecommunications Digital Data Communication and Voice Communication System GOVERNMENT OF INDIA OFFICE OF DIRECTOR GENERAL OF CIVIL AVIATION TECHNICAL CENTRE, OPP SAFDARJANG AIRPORT, NEW DELHI CIVIL AVIATION REQUIREMENTS SECTION 9 AIR SPACE AND AIR TRAFFIC MANAGEMENT SERIES 'D',

More information

UK Interface Requirement 2059

UK Interface Requirement 2059 UK Interface Requirement 2059 Ground based HF Single Sideband (SSB) radio equipment at Aeronautical Stations of the Aeronautical Mobile (R) Service for voice and data link communication. Publication date:

More information

INTERNATIONAL STANDARDS AND RECOMMENDED PRACTICES

INTERNATIONAL STANDARDS AND RECOMMENDED PRACTICES Annex or Recommended Practice Chapter 1 Definition INTERNATIONAL STANDARDS AND RECOMMENDED PRACTICES CHAPTER 1. DEFINITIONS Note. All references to Radio Regulations are to the Radio Regulations published

More information

ROM/UDF CPU I/O I/O I/O RAM

ROM/UDF CPU I/O I/O I/O RAM DATA BUSSES INTRODUCTION The avionics systems on aircraft frequently contain general purpose computer components which perform certain processing functions, then relay this information to other systems.

More information

An advisory circular may also include technical information that is relevant to the standards or requirements.

An advisory circular may also include technical information that is relevant to the standards or requirements. Advisory Circular AC91-24 Automatic Dependent Surveillance Broadcast (ADS-B) Systems Revision 0 24 July 2018 General Civil Aviation Authority advisory circulars contain guidance and information about standards,

More information

This Licence replaces the licence issued by Ofcom on 25 April 2006 to Manx Telecom Limited.

This Licence replaces the licence issued by Ofcom on 25 April 2006 to Manx Telecom Limited. Office of Communications (Ofcom) Wireless Telegraphy Act 2006 PUBLIC WIRELESS NETWORK LICENCE This Licence replaces the licence issued by Ofcom on 25 April 2006 to Manx Telecom Limited. Licence no. 0261634

More information

Aeronautical Telecommunications

Aeronautical Telecommunications International Standards and Recommended Practices Annex 10 to the Convention on International Civil Aviation Aeronautical Telecommunications Volume V Aeronautical Radio Frequency Spectrum Utilization This

More information

Radio Transmitters and Receivers Operating in the Land Mobile and Fixed Services in the Frequency Range MHz

Radio Transmitters and Receivers Operating in the Land Mobile and Fixed Services in the Frequency Range MHz Issue 11 June 2011 Spectrum Management and Telecommunications Radio Standards Specification Radio Transmitters and Receivers Operating in the Land Mobile and Fixed Services in the Frequency Range 27.41-960

More information

Ron Turner Technical Lead for Surface Systems. Syracuse, NY. Sensis Air Traffic Systems - 1

Ron Turner Technical Lead for Surface Systems. Syracuse, NY. Sensis Air Traffic Systems - 1 Multilateration Technology Overview Ron Turner Technical Lead for Surface Systems Sensis Corporation Syracuse, NY Sensis Air Traffic Systems - 1 Presentation Agenda Multilateration Overview Transponder

More information

Footnotes to National Frequency Allocation of Japan (Column 4)

Footnotes to National Frequency Allocation of Japan (Column 4) Footnotes to National Frequency Allocation of Japan (Column 4) J1 In authorizing the use of frequencies below 8.3kHz, it shall be ensured that no harmful interference is thereby caused to the services

More information

THE INTERNATIONAL COSPAS-SARSAT PROGRAMME AGREEMENT

THE INTERNATIONAL COSPAS-SARSAT PROGRAMME AGREEMENT THE INTERNATIONAL COSPAS-SARSAT PROGRAMME AGREEMENT THE INTERNATIONAL COSPAS-SARSAT PROGRAMME AGREEMENT TABLE OF CONTENTS Page PREAMBLE 1 ARTICLE 1 DEFINITIONS 2 ARTICLE 2 PURPOSE OF THE AGREEMENT 2 ARTICLE

More information

1. The Office of Communications (Ofcom) grants this wireless telegraphy licence ( the Licence ) to

1. The Office of Communications (Ofcom) grants this wireless telegraphy licence ( the Licence ) to Office of Communications (Ofcom) Wireless Telegraphy Act 2006 PUBLIC WIRELESS NETWORK LICENCE This Licence document replaces the version of the licence 1 issued by Ofcom on 22 December 2015 to Manx Telecom

More information

SwiftBroadband Safety Frequency Management

SwiftBroadband Safety Frequency Management SwiftBroadband Safety Frequency Management Presentation to ICAO ACP Working Group F 17-24 September 2012 Contents 1. Overview of SwiftBroadband Safety Service Performance and Benefits 2. How the SwiftBroadband

More information

UNMANNED AIRCRAFT SYSTEMS STUDY GROUP (UASSG)

UNMANNED AIRCRAFT SYSTEMS STUDY GROUP (UASSG) 04/09/12 UNMANNED AIRCRAFT SYSTEMS STUDY GROUP (UASSG) TENTH MEETING Rio de Janeiro, 24 to 28 September 2012 Agenda Item 3d: C3 SARPs Command and Control (C2) link provision, link certification and requirement

More information

) #(2/./53 $!4! 42!.3-)33)/.!4! $!4! 3)'.!,,).' 2!4% ()'(%2 4(!. KBITS 53).' K(Z '2/50 "!.$ #)2#5)43

) #(2/./53 $!4! 42!.3-)33)/.!4! $!4! 3)'.!,,).' 2!4% ()'(%2 4(!. KBITS 53).' K(Z '2/50 !.$ #)2#5)43 INTERNATIONAL TELECOMMUNICATION UNION )454 6 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU $!4! #/--5.)#!4)/. /6%2 4(% 4%,%(/.%.%47/2+ 39.#(2/./53 $!4! 42!.3-)33)/.!4! $!4! 3)'.!,,).' 2!4% ()'(%2 4(!.

More information

Rulemaking Hearing Rules of the Tennessee Department of Health Bureau of Health Licensure and Regulation Division of Emergency Medical Services

Rulemaking Hearing Rules of the Tennessee Department of Health Bureau of Health Licensure and Regulation Division of Emergency Medical Services Rulemaking Hearing Rules of the Tennessee Department of Health Bureau of Health Licensure and Regulation Division of Emergency Medical Services Chapter 1200-12-01 General Rules Amendments of Rules Subparagraph

More information

(Non-legislative acts) DECISIONS

(Non-legislative acts) DECISIONS 4.12.2010 Official Journal of the European Union L 319/1 II (Non-legislative acts) DECISIONS COMMISSION DECISION of 9 November 2010 on modules for the procedures for assessment of conformity, suitability

More information

Report on the Validation of the Requirements in the SARPs for UAT

Report on the Validation of the Requirements in the SARPs for UAT International Civil Aviation Organization 999 University Street Montreal, Quebec, Canada H3C 5H7 Report on the Validation of the Requirements in the SARPs for UAT Revision 2.0 4 April 2005 Prepared by:

More information

Conformity and Interoperability Training Homologation Procedures and Type Approval Testing for Mobile Terminals

Conformity and Interoperability Training Homologation Procedures and Type Approval Testing for Mobile Terminals Conformity and Interoperability Training Homologation Procedures and Type Approval Testing for Mobile Terminals ITU C&I Programme Training Course on Testing Mobile Terminal Schedule RF Tests (Functional)

More information

ICAO Handbook on Radio Frequency Spectrum Requirements for Civil Aviation Vol. I - ICAO Spectrum Strategy Vol. II - Frequency Planning

ICAO Handbook on Radio Frequency Spectrum Requirements for Civil Aviation Vol. I - ICAO Spectrum Strategy Vol. II - Frequency Planning ICAO Handbook on Radio Frequency Spectrum Requirements for Civil Aviation Vol. I - ICAO Spectrum Strategy Vol. II - Frequency Planning 100 khz 200 khz 300 khz 400 khz 600 khz 800 khz 1 MHz 2 MHz 3 MHz

More information

General Class Element 3 Course Prese t n t a i tion ELEMENT 3 SUB ELEMENTS G1 Commission s Rules G2 Oper t a i

General Class Element 3 Course Prese t n t a i tion ELEMENT 3 SUB ELEMENTS G1 Commission s Rules G2 Oper t a i General Class Element 3 Course Presentation ti ELEMENT 3 SUB ELEMENTS General Licensing Class Subelement G1 Commission s s Rules 5 Exam Questions, 5 Groups G1 G2 Operating Procedures G3 Radio Wave Propagation

More information

EE Chapter 14 Communication and Navigation Systems

EE Chapter 14 Communication and Navigation Systems EE 2145230 Chapter 14 Communication and Navigation Systems Two way radio communication with air traffic controllers and tower operators is necessary. Aviation electronics or avionics: Avionic systems cover

More information

RECOMMENDATION ITU-R S.1594 *

RECOMMENDATION ITU-R S.1594 * Rec. ITU-R S.1594 1 RECOMMENDATION ITU-R S.1594 * Maximum emission levels and associated requirements of high density fixed-satellite service earth stations transmitting towards geostationary fixed-satellite

More information

Future Communications Infrastructure - Technology Investigations Description of AMACS

Future Communications Infrastructure - Technology Investigations Description of AMACS EUROPEAN ORGANISATION FOR THE SAFETY OF AIR NAVIGATION EUROCONTROL Future Communications Infrastructure - Technology Investigations Edition Number : 1.0 Edition Date : 02/07/07 Status : Issue Intended

More information

Consultation Paper on Using a Portion of the Band GHz for Tactical Common Data Link (TCDL) Systems

Consultation Paper on Using a Portion of the Band GHz for Tactical Common Data Link (TCDL) Systems December 2008 Spectrum Management and Telecommunications Consultation Paper on Using a Portion of the Band 14.5-15.35 GHz for Tactical Common Data Link (TCDL) Systems Aussi disponible en français Department

More information

RECOMMENDATION ITU-R M.1184

RECOMMENDATION ITU-R M.1184 Rec. ITU-R M.1184 1 RECOMMENDATION ITU-R M.1184 TECHNICAL CHARACTERISTICS OF MOBILE SATELLITE SYSTEMS IN THE 1-3 GHz RANGE FOR USE IN DEVELOPING CRITERIA FOR SHARING BETWEEN THE MOBILE-SATELLITE SERVICE

More information

HD Radio FM Transmission System Specifications

HD Radio FM Transmission System Specifications HD Radio FM Transmission System Specifications Rev. D February 18, 2005 Doc. No. SY_SSS_1026s TRADEMARKS The ibiquity Digital logo and ibiquity Digital are registered trademarks of ibiquity Digital Corporation.

More information

EUROPEAN pr ETS TELECOMMUNICATION February 1996 STANDARD

EUROPEAN pr ETS TELECOMMUNICATION February 1996 STANDARD FINAL DRAFT EUROPEAN pr ETS 300 118 TELECOMMUNICATION February 1996 STANDARD Second Edition Source: ETSI TC-TE Reference: RE/TE-05049 ICS: 33.020 Key words: PSTN, modems Public Switched Telephone Network

More information

CONSIDERATION OF THE OUTCOME OF WRC-12 AND PREPARATION OF INITIAL ADVICE ON A DRAFT IMO POSITION ON WRC-2015 AGENDA ITEMS

CONSIDERATION OF THE OUTCOME OF WRC-12 AND PREPARATION OF INITIAL ADVICE ON A DRAFT IMO POSITION ON WRC-2015 AGENDA ITEMS E JOINT IMO/ITU EXPERTS GROUP ON MARITIME RADIOCOMMUNICATION MATTERS 8th session Agenda item 5 IMO/ITU EG 8/5/8 5 September 2012 ENGLISH ONLY CONSIDERATION OF THE OUTCOME OF WRC-12 AND PREPARATION OF INITIAL

More information

Digital Audio Broadcasting Eureka-147. Minimum Requirements for Terrestrial DAB Transmitters

Digital Audio Broadcasting Eureka-147. Minimum Requirements for Terrestrial DAB Transmitters Digital Audio Broadcasting Eureka-147 Minimum Requirements for Terrestrial DAB Transmitters Prepared by WorldDAB September 2001 - 2 - TABLE OF CONTENTS 1 Scope...3 2 Minimum Functionality...3 2.1 Digital

More information

RECOMMENDATION ITU-R BT.1302 *

RECOMMENDATION ITU-R BT.1302 * Rec. ITU-R BT.1302 1 RECOMMENDATION ITU-R BT.1302 * Interfaces for digital component video signals in 525-line and 625-line television systems operating at the 4:2:2 level of Recommendation ITU-R BT.601

More information

Portable Test Equipment

Portable Test Equipment Portable Test Equipment Solutions www.airtel-atn.com Portable Test Equipment The implementation of the Data Link is one of the key methods to significantly reduce the congestion and improve safety in the

More information

This Licence replaces the licence issued by Ofcom on 22 April 2013 to British Telecommunications PLC.

This Licence replaces the licence issued by Ofcom on 22 April 2013 to British Telecommunications PLC. Office of Communications (Ofcom) Wireless Telegraphy Act 2006 SPECTRUM ACCESS 2.6 GHz LICENCE This Licence replaces the licence issued by Ofcom on 22 April 2013 to British Telecommunications PLC. Licence

More information

Frequency Synchronization in Global Satellite Communications Systems

Frequency Synchronization in Global Satellite Communications Systems IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 51, NO. 3, MARCH 2003 359 Frequency Synchronization in Global Satellite Communications Systems Qingchong Liu, Member, IEEE Abstract A frequency synchronization

More information

Automatic Dependent Surveillance -ADS-B

Automatic Dependent Surveillance -ADS-B ASECNA Workshop on ADS-B (Dakar, Senegal, 22 to 23 July 2014) Automatic Dependent Surveillance -ADS-B Presented by FX SALAMBANGA Regional Officer, CNS WACAF OUTLINE I Definition II Principles III Architecture

More information

RECOMMENDATION ITU-R M.1167 * Framework for the satellite component of International Mobile Telecommunications-2000 (IMT-2000)

RECOMMENDATION ITU-R M.1167 * Framework for the satellite component of International Mobile Telecommunications-2000 (IMT-2000) Rec. ITU-R M.1167 1 RECOMMENDATION ITU-R M.1167 * Framework for the satellite component of International Mobile Telecommunications-2000 (IMT-2000) (1995) CONTENTS 1 Introduction... 2 Page 2 Scope... 2

More information

CDMA Principle and Measurement

CDMA Principle and Measurement CDMA Principle and Measurement Concepts of CDMA CDMA Key Technologies CDMA Air Interface CDMA Measurement Basic Agilent Restricted Page 1 Cellular Access Methods Power Time Power Time FDMA Frequency Power

More information

Chapter 6 Solution to Problems

Chapter 6 Solution to Problems Chapter 6 Solution to Problems 1. You are designing an FDM/FM/FDMA analog link that will occupy 36 MHz of an INTELSAT VI transponder. The uplink and downlink center frequencies of the occupied band are

More information

Adoption of this document as basis for broadband wireless access PHY

Adoption of this document as basis for broadband wireless access PHY Project Title Date Submitted IEEE 802.16 Broadband Wireless Access Working Group Proposal on modulation methods for PHY of FWA 1999-10-29 Source Jay Bao and Partha De Mitsubishi Electric ITA 571 Central

More information

CH 4. Air Interface of the IS-95A CDMA System

CH 4. Air Interface of the IS-95A CDMA System CH 4. Air Interface of the IS-95A CDMA System 1 Contents Summary of IS-95A Physical Layer Parameters Forward Link Structure Pilot, Sync, Paging, and Traffic Channels Channel Coding, Interleaving, Data

More information

UK Broadband Limited Company Reg No: Spectrum Access 3.5 GHz Licence First Issued: 28/02/17 Licence Number: Rev 1: 11/01/18

UK Broadband Limited Company Reg No: Spectrum Access 3.5 GHz Licence First Issued: 28/02/17 Licence Number: Rev 1: 11/01/18 Office of Communications (Ofcom) Wireless Telegraphy Act 2006 UK Broadband Limited Company Reg No: 04713634 Licence Category: SPECTRUM ACCESS 3.5 GHz This Licence replaces the version of the licence issued

More information

RECOMMENDATION ITU-R BT *

RECOMMENDATION ITU-R BT * Rec. ITU-R BT.656-4 1 RECOMMENDATION ITU-R BT.656-4 * Interfaces for digital component video signals in 525-line and 625-line television systems operating at the 4:2:2 level of Recommendation ITU-R BT.601

More information

EVOLUTION OF AERONAUTICAL SURVEILLANCE

EVOLUTION OF AERONAUTICAL SURVEILLANCE EVOLUTION OF AERONAUTICAL SURVEILLANCE By: M. Paydar ICAO December 2010 Aeronautical Surveillance Airborne Surveillance Identification Position (at what time?) Additional info (e.g. velocity) Ground Surveillance

More information

IMO RESOLUTION A.1001(25) Adopted on 29 November 2007 (Agenda item 9)

IMO RESOLUTION A.1001(25) Adopted on 29 November 2007 (Agenda item 9) INTERNATIONAL MARITIME ORGANIZATION E IMO ASSEMBLY 25th session Agenda item 9 A 25/Res.1001 3 January 2008 Original: ENGLISH RESOLUTION A.1001(25) Adopted on 29 November 2007 (Agenda item 9) CRITERIA FOR

More information

CHAPTER -15. Communication Systems

CHAPTER -15. Communication Systems CHAPTER -15 Communication Systems COMMUNICATION Communication is the act of transmission and reception of information. COMMUNICATION SYSTEM: A system comprises of transmitter, communication channel and

More information

ETSI Standards and the Measurement of RF Conducted Output Power of Wi-Fi ac Signals

ETSI Standards and the Measurement of RF Conducted Output Power of Wi-Fi ac Signals ETSI Standards and the Measurement of RF Conducted Output Power of Wi-Fi 802.11ac Signals Introduction The European Telecommunications Standards Institute (ETSI) have recently introduced a revised set

More information

Muscle Shoals Amateur Radio Club. Extra License Class Training Session 1

Muscle Shoals Amateur Radio Club. Extra License Class Training Session 1 Muscle Shoals Amateur Radio Club Extra License Class Training Session 1 Overview Introductions Format Syllabus Questions Introductions EMA Director, George Grabyran Coordinator and Instructors MSARC Officers

More information

Exam questions: AE3-295-II

Exam questions: AE3-295-II Exam questions: AE3-295-II 1. NAVIGATION SYSTEMS (30 points) In this question we consider the DME radio beacon. [a] What does the acronym DME stand for? (3 points) DME stand for Distance Measuring Equipment

More information

AMCP/8-WP/66. APPENDIX (English only) COMPARATIVE ANALYSIS OF ADS-B LINKS

AMCP/8-WP/66. APPENDIX (English only) COMPARATIVE ANALYSIS OF ADS-B LINKS Appendix to the Report on Agenda Item 4 4A-1 APPENDIX (English only) COMPARATIVE ANALYSIS OF ADS-B LINKS References 1. Air Navigation Commission Minutes of the Eleventh Meeting of the 160th Session. 2.

More information

1. The Office of Communications (Ofcom) grants this wireless telegraphy licence ( the Licence ) to

1. The Office of Communications (Ofcom) grants this wireless telegraphy licence ( the Licence ) to Office of Communications (Ofcom) Wireless Telegraphy Act 2006 Telefónica UK Limited - Public Wireless Network Licence PUBLIC WIRELESS NETWORK LICENCE This Licence document replaces the version of the Licence

More information

DYNAMIC BANDWIDTH ALLOCATION IN SCPC-BASED SATELLITE NETWORKS

DYNAMIC BANDWIDTH ALLOCATION IN SCPC-BASED SATELLITE NETWORKS DYNAMIC BANDWIDTH ALLOCATION IN SCPC-BASED SATELLITE NETWORKS Mark Dale Comtech EF Data Tempe, AZ Abstract Dynamic Bandwidth Allocation is used in many current VSAT networks as a means of efficiently allocating

More information

Fiscal 2007 Environmental Technology Verification Pilot Program Implementation Guidelines

Fiscal 2007 Environmental Technology Verification Pilot Program Implementation Guidelines Fifth Edition Fiscal 2007 Environmental Technology Verification Pilot Program Implementation Guidelines April 2007 Ministry of the Environment, Japan First Edition: June 2003 Second Edition: May 2004 Third

More information

Reducing Test Flights Using Simulated Targets and a Carefully Chosen Set-up

Reducing Test Flights Using Simulated Targets and a Carefully Chosen Set-up Reducing Test Flights Using Simulated Targets and a Carefully Chosen Set-up Edition: 001 Date: 18-FEB-09 Status: Released DOCUMENT DESCRIPTION Document Title Reducing Test Flights: Using Simulated Targets

More information

Radiocommunications Licence Conditions (Amateur Licence) Determination No. 1 of 1997

Radiocommunications Licence Conditions (Amateur Licence) Determination No. 1 of 1997 Radiocommunications Licence Conditions (Amateur Licence) Determination No. 1 of 1997 as amended made under paragraph 107 (1) (f) and subsection 179 (1) of the Radiocommunications Act 1992 This compilation

More information

ETSI SMG#24 TDoc SMG 903 / 97. December 15-19, 1997 Source: SMG2. Concept Group Alpha - Wideband Direct-Sequence CDMA: System Description Summary

ETSI SMG#24 TDoc SMG 903 / 97. December 15-19, 1997 Source: SMG2. Concept Group Alpha - Wideband Direct-Sequence CDMA: System Description Summary ETSI SMG#24 TDoc SMG 903 / 97 Madrid, Spain Agenda item 4.1: UTRA December 15-19, 1997 Source: SMG2 Concept Group Alpha - Wideband Direct-Sequence CDMA: System Description Summary Concept Group Alpha -

More information

A Review of Vulnerabilities of ADS-B

A Review of Vulnerabilities of ADS-B A Review of Vulnerabilities of ADS-B S. Sudha Rani 1, R. Hemalatha 2 Post Graduate Student, Dept. of ECE, Osmania University, 1 Asst. Professor, Dept. of ECE, Osmania University 2 Email: ssrani.me.ou@gmail.com

More information

ETSI EN V1.2.1 ( )

ETSI EN V1.2.1 ( ) Candidate Harmonized European Standard (Telecommunications series) Electromagnetic compatibility and Radio spectrum Matters (ERM); ElectroMagnetic Compatibility (EMC) standard for radio equipment and services;

More information

SATELLITE COMMUNICATIONS

SATELLITE COMMUNICATIONS SATELLITE COMMUNICATIONS Timothy Pratt Charles W. Bostian Department of Electrical Engineering Virginia Polytechnic Institute and State University JOHN WILEY & SONS New York Chichester Brisbane Toronto

More information